[Federal Register Volume 65, Number 61 (Wednesday, March 29, 2000)]
[Rules and Regulations]
[Pages 16736-16756]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-7595]



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Part III





Department of Transportation





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Federal Aviation Administration



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14 CFR Parts 91, 121, 135



Terrain Awareness and Warning System; Final Rule

  Federal Register / Vol. 65, No. 61 / Wednesday, March 29, 2000 / 
Rules and Regulations  

[[Page 16736]]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Parts 91, 121, 135

[Docket No. 29312; Amendment No. 91-263; 121-273; 135-75]
RIN 2120-AG46


Terrain Awareness and Warning System

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The Federal Aviation Administration (FAA) is amending the 
operating rules to require that certain airplanes be equipped with an 
FAA-approved terrain awareness and warning system (also referred to as 
an enhanced ground proximity warning system). This final rule is a 
general aviation regulation that affects all U.S. registered turbine-
powered airplanes with six or more passenger seats (exclusive of pilot 
and copilot seating). This change is in response to several accident 
investigations and studies that have shown a need to expand the safety 
benefits of ground proximity warning systems to certain additional 
operations. These investigations and studies have also shown that there 
is a need to increase the warning times and situational awareness of 
flight crews to decrease the risk of controlled flight into terrain 
accidents.

EFFECTIVE DATE: March 29, 2001.

FOR FURTHER INFORMATION CONTACT: Manuel Macedo, Aircraft Engineering 
Division, AIR-100, Aircraft Certification Service, Federal Aviation 
Administration, 800 Independence Avenue, SW., Washington, DC 20591; 
Telephone: (202) 267-9566.

SUPPLEMENTARY INFORMATION:

Availability of Final Rules

    An electronic copy of this document may be downloaded using a modem 
and suitable communications software from the FAA regulations section 
of the FedWorld electronic bulletin board service (telephone: (703) 
321-3339) or the Government Printing Office's (GPO) electronic bulletin 
board service (telephone: (202) 512-1661).
    Internet users may reach the FAA's web page at http://www.faa.gov/avr/arm/nprm/nprm.htm or the GPO's web page at http://www.access.gpo.gov/nara for access to recently published rulemaking 
documents.
    Any person may obtain a copy of this document by submitting a 
request to the Federal Aviation Administration, Office of Rulemaking, 
ARM-1, 800 Independence Avenue, SW., Washington, DC 20591, or by 
calling (202) 267-9680. Communications must identify the amendment 
number or docket number of this final rule.
    Persons interested in being placed on the mailing list for future 
rulemaking documents should request from the above office a copy of 
Advisory Circular No. 11-2A, Notice of Proposed Rulemaking Distribution 
System, which describes the application procedure.

Small Business Regulatory Enforcement Fairness Act

    The Small Business Regulatory Enforcement Fairness Act (SBREFA) of 
1996, requires the FAA to comply with small entity requests for 
information or advice about compliance with statutes and regulations 
within its jurisdiction. Therefore, any small entity that has a 
question regarding this document may contact their local FAA official. 
Internet users can find additional information on SBREFA on the FAA's 
web page at http://www.faa.gov/avr/arm/sbrefa.htm and may send 
electronic inquiries to the following Internet address: [email protected]

Background

    Beginning in the early 1970's, a number of studies looked at the 
occurrence of ``controlled flight into terrain'' (CFIT) accidents, 
where a properly functioning airplane under the control of a fully 
qualified and certificated crew is flown into terrain (or water or 
obstacles) with no apparent awareness on the part of the crew.
    Findings from these studies indicated that many such accidents 
could have been avoided if a warning device called a ground proximity 
warning system (GPWS) had been used. As a result of these studies and 
recommendations from the National Transportation Safety Board (NTSB), 
in 1974 the FAA required all part 121 certificate holders (i.e., those 
operating large turbine-powered airplanes) and some part 135 
certificate holders (i.e., those operating large turbojet airplanes) to 
install Technical Standard Order (TSO) approved GPWS equipment 
(Secs. 121.360 and 135.153). (39 FR 44439, December 18, 1974).
    In 1978 the FAA extended the GPWS requirement to part 135 
certificate holders operating smaller airplanes: turbojet-powered 
airplanes with 10 or more passenger seats. These operators were 
required to install TSO-approved GPWS equipment or alternative ground 
proximity advisory systems that provide routine altitude callouts 
whether or not there is any imminent danger (Sec. 135.153). (43 FR 
28176, June 29, 1978). This requirement was considered necessary 
because of the complexity, size, speed, and flight performance 
characteristics of these airplanes. The GPWS equipment was considered 
essential in helping the pilots of these airplanes to regain altitude 
quickly and avoid what could have been a CFIT accident.
    Installation of GPWS's or alternative FAA-approved advisory systems 
was not required on turbo-propeller powered (turboprop) airplanes 
operated under part 135 because, at that time, the general consensus 
was that the performance characteristics of turboprop airplanes made 
them less susceptible to CFIT accidents. For example, it was thought 
that turboprop airplanes had a greater ability to respond quickly in 
situations where altitude control was inadvertently neglected, as 
compared to turbojet airplanes. However later studies, including 
investigations by the NTSB, analyzed CFIT accidents involving turboprop 
airplanes and found that many of these accidents could have been 
avoided if GPWS equipment had been used.
    Some of these studies also compared the effectiveness of the 
alternative ground proximity advisory system to the GPWS. GPWS was 
found to be superior in that it would warn only when necessary, provide 
maximum warning time with minimal unwanted alarms, and use command-type 
warnings.
    Based on these reports and NTSB recommendations, in 1992 the FAA 
amended Sec. 135.153 to require GPWS equipment on all turbine-powered 
airplanes with 10 or more passenger seats. (57 FR 9944, March 20, 
1992).
    After the current rules were issued, advances in terrain mapping 
technology permitted the development of a new type of ground proximity 
warning system that provides greater situational awareness for flight 
crews. The FAA has approved certain installations of this type of 
equipment, known as the enhanced ground proximity warning system 
(EGPWS). However, in this final rule, the FAA is using the broader term 
``terrain awareness and warning system'' (TAWS) because the FAA expects 
that a variety of systems may be developed in the near future that 
would meet the improved standards contained in this final rule.
    The TAWS improves on existing GPWS systems by providing the flight 
crew much earlier aural and visual warning of impending terrain, 
forward looking capability, and continued operation in the landing 
configuration. These improvements provide more time

[[Page 16737]]

for the flight crew to make smoother and gradual corrective action.
    In 1998, the FAA issued Notice No. 98-11, Terrain Awareness and 
Warning System (63 FR 45628, August 26, 1998), proposing that all 
turbine-powered U.S.-registered airplanes type certificated to have six 
or more passenger seats (exclusive of pilot and copilot seating), be 
equipped with an FAA-approved terrain awareness and warning system. 
This final rule is based on Notice No. 98-11.

NTSB Recommendations

    Following the investigation of a CFIT accident south of Dulles 
International Airport on June 18, 1994, involving a Learjet 25D in 
which there were 12 fatalities, the NTSB recommended (Recommendation A-
95-35) that the FAA mandate that all turbojet-powered airplanes 
equipped with six or more passenger seats have an operating ground 
proximity warning system installed. That recommendation also made 
reference to an earlier, similar NTSB recommendation (Recommendation A-
92-55) resulting from a 1991 CFIT accident involving a Beechjet 400. 
Both planes were corporate jets flying under part 91 and were not 
required to have GPWS equipment installed.
    More recently, the NTSB issued Recommendation A-96-101, based on 
its investigation of a CFIT accident northeast of Cali, Columbia, on 
December 20, 1995, involving an American Airlines Boeing 757 airplane 
operating under part 121, which resulted in 159 fatalities. Although 
the airplane involved in the accident was equipped with the mandatory 
GPWS, the GPWS did not provide the warning in time for the crew to 
avoid the mountainous terrain. The NTSB recommended that the FAA 
examine the effectiveness of the enhanced ground proximity warning 
system, and if found effective, require all transport-category airplane 
to be equipped with this system.

Volpe National Transportation Systems Center Studies

    In recent years, the FAA commissioned two studies by the Department 
of Transportation's (DOT) Volpe National Transportation Systems Center 
(VNTSC) to examine the effectiveness of GPWS and EGPWS in preventing 
CFIT accidents in various airplane categories and operations. The two 
studies, hereafter called the Volpe part 91 study and the Volpe part 
121/135 study, analyzed CFIT accidents during the period 1985-1995 and 
found that EGPWS could have prevented 95-100 percent of these 
accidents. (For more detail on these studies, see: DOT-TSC-FA6D1-96-01, 
and DOT-TSC-FA6D1-96-03, both entitled, ``Investigation of Controlled 
Flight Into Terrain'', which are included in the public docket.)
    In the Volpe part 91 study VNTSC concluded that ``equipping 
aircraft with GPWS, or EGPWS when it becomes available, could be a 
particularly effective means of preventing CFIT accidents in the 
subject FAR Part 91 aircraft fleet.'' Likewise, in the Volpe part 121/
135 study, VNTSC concluded that there was compelling evidence of the 
potential effectiveness of EGPWS in preventing CFIT accidents because 
the equipment would have provided the same or increased warning 
durations over GPWS. In addition, flight crews, given a continuous 
terrain display, could have responded to terrain threats well before an 
EGPWS alert.

Discussion of Comments

    The FAA received over 200 comments in response to the Terrain 
Awareness and Warning System NPRM (63 FR 45628, August 26, 1998). After 
careful analysis of these comments, the FAA has made the following 
changes between the NPRM and the final rule:
    1. The final rule is not applicable to parachute operations, aerial 
application operations, and firefighting operations.
    2. The final rule is applicable to airplanes ``configured'' with 6 
or more passenger seats, not to airplanes ``type certificated'' for 6 
or more passenger seats.
    3. The final rule addresses two classes of TAWS equipment, Class A 
and Class B. A new TSO, TSO-C151, includes the airworthiness 
requirements for both Class A and Class B equipment. Class A equipment 
will be required for airplanes operated under part 121 and part 135 of 
10 or more passenger seats; this class of equipment will be the same as 
originally proposed. Class A equipment includes current GPWS required 
functions. Installers of Class A equipment required by this rule must 
install a terrain situational awareness display. Class B equipment will 
be required for airplanes operated under part 91 with 6 or more 
passenger seats and for airplanes operated under part 135 with 6-9 
passenger seats. Class B equipment includes the basic TAWS safety 
features. These changes, in response to the comments, for airplanes 
operated under part 91 with 6 or more passenger seats and airplanes 
operated under part 135 with 6-9 passenger seats, will reduce the 
initial cost of purchasing and installing TAWS, while continuing to 
provide the desired level of safety.
    A summary of the comments and an explanation of the changes made in 
the final rule in response to those comments appear below.
    Approximately one-half of the comments were from individuals 
associated with parachute operations (skydivers and parachutists; 
skydiving and parachute operators; and associations). In addition, a 
total of 254 form letters from parachute participants and operators 
were submitted opposing the installation of TAWS or EGPWS in turbine-
powered airplanes used in parachute activities. These commenters state 
that the proposed rule would be financially burdensome and would add no 
foreseeable safety benefit to parachute operations.
    The remaining comments were from various part 91 and part 135 
operators (e.g., cargo, charter, and corporate operations) and their 
representative organizations; some part 121 operators and/or their 
representatives; and a comment from an EGPWS manufacturer, Allied 
Signal.
    The following discussion summarizes these comments by the following 
issue areas: Applicability; Comments to NTSB recommendations; NPRM 
accident analysis; Comments on Cost of TAWS; GPWS/TAWS technology; TSO 
comments; supplemental type certificates; training; other government/
industry efforts; compliance schedule; and miscellaneous comments.

Applicability

    The FAA proposed adding Secs. 91.223, 121.354, and 135.154 to 
require the installation of FAA-approved terrain awareness and warning 
systems (TAWS) on certain airplanes. For operations under part 121, the 
rule would apply to all turbine-powered airplanes. For all other 
operations (parts 91, 125, 129, and 135) the FAA proposed that the rule 
apply to all turbine-powered airplanes type certificated to have six or 
more passenger seats, excluding any pilot seat.

Applicability to the Parachute Industry

    Parachute operators and parachutists say that they should be exempt 
from the proposed rule. They state that the nature of parachute 
operations makes GPWS and TAWS unnecessary. The U.S. Parachute 
Association (USPA) and the Parachute Industry Association strongly 
object to the mandatory installation of TAWS for airplanes used in 
parachute operations. The following arguments are presented by the 
parachute industry:
     Parachuting is primarily a visual flight rules (VFR) 
activity, conducted during the day, during which terrain is always 
visible and weather conditions

[[Page 16738]]

are good. Occasionally, parachute operators fly in instrument flight 
rules (IFR) conditions, e.g., to ferry an airplane, but these 
operations are performed with no passengers.
     Parachuting is primarily done in the proximity of the 
departure airport (usually within a 10-mile radius) and the pilots are 
familiar with the obstacles and terrain features around their home 
fields.
     Parachutists are the passengers in these airplanes (not 
the traveling public, which the proposed rule is seeking to protect). 
These airplanes are used only as a means for the parachutists to get to 
altitude for jumping.
     Parachute operations have not been associated with CFIT 
accidents. Some commenters state that the NPRM cites no such accidents 
in parachute operations. Therefore, the commenters do not believe GPWS 
or TAWS would have made a difference in the outcomes of any accidents 
involving parachute operations.
    USPA and other commenters from the parachute industry go on to say 
that since TAWS would provide no safety benefit to parachute 
operations, they should not have to bear the cost of installing TAWS on 
these airplanes. Some commenters add that these costs would be 
especially burdensome to small operators who already have a very small 
profit margin, which could result in their going out of business. 
Several commenters believe that the cost of installing TAWS on turbine-
powered airplanes used in parachute operations could result in some 
operators switching back to using older and smaller non-turbine 
airplanes, which would have a negative effect on the growth and safety 
of the parachute industry.
    The FAA agrees with the commenters. Parachute and skydiving 
operations are unique in that operations are conducted under VFR 
conditions, in close proximity to the home field, with constant 
reference to the ground. Furthermore, there are only a small number of 
airplanes involved in these types of operations. The FAA has changed 
Sec. 91.223 in the final rule to exclude airplanes when used for 
parachute operations and operated within 50 miles of the home airport.

Applicability to Other Part 91 Operations

    The National Business Aviation Association (NBAA) recommends that 
the FAA exempt turbine-powered airplanes operated under part 91 from 
the rule because part 91 allows operators the flexibility ``to equip 
their aircraft as necessary to accomplish the missions set forth by the 
company.'' The NBAA cites the safety record of corporate operations 
under part 91. The Aircraft Owners and Pilots Association (AOPA) 
recommends applying the proposed rule only to large turbojet airplanes 
used in commercial passenger-carrying operations. Several other part 91 
operators also state that they should be exempt from the proposed rule.
    The FAA disagrees with these commenters for the following reasons: 
(1) Two of the three NTSB recommendations discussed earlier were based 
on CFIT accidents involving airplanes operating under part 91. (2) The 
number of CFIT accidents occurring in part 91 operations is excessively 
high. (3) The Volpe part 91 study provides evidence that TAWS would 
have prevented 95 percent of the CFIT accidents studied.
    Raytheon Aircraft Company (Raytheon) recommends applying the 
proposed rule to airplanes operated under part 135 and part 121 and 
exempting part 91 operations. Raytheon requests that the FAA make 
available the data it compiled from the Volpe part 91 study of the 
forty-four accidents which was stated in the NPRM, before issuing any 
final rule for part 91 operations.
    Raytheon proposes excluding turbo-propeller airplanes operated 
under part 91 from the requirement of installing TAWS. As a second 
alternative, Raytheon proposes applying this requirement to turbine 
airplanes categorized at a minimum gross weight of 19,000 pounds 
(maximum certificated weight for a commuter category airplane), or a 
minimum gross weight of 12,500 pounds (FAA's defined certificated 
weight of a large airplane). Some commenters state that CFIT accidents 
have not been a problem for part 91 operations and that GPWS/TAWS is 
therefore unnecessary.
    The FAA disagrees with Raytheon and other commenters who oppose 
TAWS on turboprop airplanes and has determined that turboprop airplanes 
should continue to be covered. A study done for the FAA as part of the 
1992 rulemaking amending part 135, requiring GPWS equipment, revealed 
that turboprop airplanes have just as many, if not more CFIT accidents 
than turbojet airplanes. In fact, the Volpe part 91 study shows that 33 
of 44 CFIT accidents involved turboprop airplanes.
    A part 91 turboprop airplane operator states that he operates his 
airplanes in familiar terrain and that GPWS is unnecessary for his 
operations. The operator is involved in aerial applications and states 
that his operations are within 50 feet of the ground which would result 
in continuous nuisance alerting from TAWS; therefore this equipment is 
unnecessary. This commenter adds that the rule should make exceptions 
for operations such as his which operate airplanes with a payload 
capacity in excess of 6,000 pounds.
    The FAA agrees with the commenter that operations involving aerial 
applications should be excluded. Therefore the final rule has been 
changed in Sec. 91.223 so that it does not apply to airplanes used in 
aerial applications or agricultural operations.
    Raytheon and others recommend rewording ``type certificated with  * 
* * .'' to read ``configured with * * *.'' These commenters say that 
rewording the text will permit the type of TAWS equipment installed to 
be determined by the number of seats installed in the airplane, rather 
than the maximum number of seats permitted by the certification basis. 
Similarly, the Regional Airline Association (RAA) and a part 135 cargo 
operator, request that proposed Secs. 91.223 and 135.154 be revised to 
replace ``certificated to have'' with ``having.''
    Federal Express believes that airplanes type-certificated as cargo 
airplanes that do not carry passengers should not be required to 
install TAWS as proposed by the NPRM. Federal Express also believes 
that the Fokker airplanes, which were converted from a passenger to a 
cargo-only configuration, should not have been covered by the NPRM. 
Federal Express requests the FAA to amend the NPRM to expressly exclude 
cargo-only airplanes.
    The FAA agrees with the commenters' recommendations that the 
equipment requirements be determined by the number of seats. The FAA 
has changed the final rule in Secs. 91.223 and 135.154 so that the 
words ``type-certificated to have six or more passenger seats'' are 
changed to ``configured with six or more passenger seats.''
    In response to Federal Express and others who state that passenger-
carrying planes converted to cargo planes should not have to comply 
with the rule, the FAA partially agrees in that if the airplane (cargo 
carrying or not) is configured with fewer than 6 passenger seats and is 
operating under part 91, then TAWS is not required. However, for 
operations conducted under part 121 (cargo carrying or not), TAWS is 
required regardless of the number of passenger seats. Under existing 
rules, the FAA requires GPWS for part 121 regardless of the number of 
seats and is continuing to maintain the same safety standard.

[[Page 16739]]

    In addition many airplanes operating under part 121 have older 
model GPWS equipment. Some of the NTSB recommendations discussed 
earlier include sub-recommendations that the FAA mandate replacement of 
the older equipment with more modern equipment. This final rule also 
responds to such recommendations.
    The FAA disagrees with the commenter that cargo airplanes should be 
exempt from the rule. Specifically in Sec. 121.360, the use of GPWS is 
required on turbine-powered airplanes operated under part 121. In this 
rule the FAA is maintaining the existing GPWS requirements (which also 
meets the ICAO requirements) by requiring TAWS that includes GPWS 
functions.

Applicability to Part 135 Operations

    The National Air Transportation Association (NATA) and several part 
135 operators ask why the FAA has put part 135 operators into the same 
category as part 91 operators. These commenters object to the FAA's use 
of part 91 accident statistics to justify requiring TAWS for them. The 
NATA states that the premise for this rulemaking is unfounded due to 
the FAA's failure to specifically review the part 135 on-demand 
community. The NATA contends that the lack of consideration of these 
specific types of airplanes and operations fails to provide complete 
data that is necessary to justify the application of a rule of this 
magnitude to this industry segment.
    The NATA recommends that the FAA conduct a study of accidents 
involving airplanes operated on-demand under part 135. These commenters 
suggest that a new cost/benefit analysis, and a new Initial Regulatory 
Flexibility Determination and Analysis based on the study suggested 
would provide an accurate representation of the true cost to part 135 
operators. The NATA's position is supported by a number of part 135 on-
demand charter operators.
    A charter operation states that turbine-powered airplanes with 
fewer than 10 seats should not be required to install GPWS/TAWS because 
most CFIT accidents have involved large commercial jets.
    The Helicopter Association International (HAI) supports the 
position of the Alaska Air Carriers Association (AACA) and others who 
want part 135 operators exempt from the TAWS requirement. The HAI says 
that ``industry and government resources are finite, and that TAWS does 
not promise to advance the cause of aviation safety enough to justify 
the costs involved at this time.''
    In the preliminary regulatory analysis the FAA did not specifically 
evaluate part 135 accidents. However, the FAA determined that the 
airplanes that are frequently found in part 135 on-demand operations 
are the same type that are typically operated in part 91. Therefore, 
the FAA extended the part 91 analysis to part 135 operations.
    The operating rules of part 91 apply to all airplanes, including 
those operated under parts 121 and 135. The Volpe part 91 study 
supports the use of this equipment on the types of airplanes used by 
both parts 91 and 135.
    In addition, the Volpe studies confirmed that compared to the GPWS, 
the TAWS equipment provides earlier audio and visual alerts. In fact, 
in the Volpe part 91 study the GPWS system used for comparison purposes 
was the most advanced GPWS system. In reality many of the GPWS systems 
in service are the older versions that have been plagued with nuisance 
and false alarms.
    The HAI opposes any attempt to extend the TAWS requirement to 
rotorcraft and says that the decision whether to use TAWS should be 
left up to each rotorcraft operator ``who is best able to weigh the 
substantial costs involved against the safety benefit that may be 
obtained.''
    In response to HAI's comment on requiring TAWS for rotorcraft, the 
FAA did not receive any comments that would justify extending this rule 
to rotorcraft at this time.
    A commenter that operates a Pilatus/Fairchild PC-6 with a maximum 
of 11 seats, is against requiring TAWS for ``charter in the bush'' type 
operations. The commenter says that ``the PC-6 was designed to land on 
most of the terrain a Ground Proximity Warning System would request a 
pilot to avoid.''
    The FAA disagrees. This type of operation is ideal for use of TAWS 
equipment because bush flying frequently involves operating over rugged 
terrain where TAWS is most valuable. However, for the landing phase of 
these types of operations, it is possible to customize the terrain data 
base during the installation approval process.
    One commenter says that there are many part 135 small airplane 
freight operators who use airplanes that are not required to have radar 
equipment installed; and these airplanes often have entirely mechanical 
instrument panels. The commenter concludes that, these airplanes would 
not be equipped to provide a display.
    The FAA has determined that airplanes configured for fewer than 6 
seats and operated under part 91 or part 135 should continue to operate 
without a terrain awareness and warning system. These airplanes are not 
affected by this rulemaking action. In addition, the FAA has modified 
the requirement for airplanes configured with 10 or more seats under 
part 135. These airplanes must be operated with a terrain situational 
display to meet the requirements of this rule.

Applicability to Turbo-Propeller Airplanes

    Piedmont Airlines, in conjunction with US Airways, proposes 
exempting turbo-propeller airplanes from the proposed rule because many 
of these airplanes have only recently been equipped with GPWS. This 
commenter questions the benefit of replacing later generation GPWS with 
TAWS when the effectiveness of the newly installed GPWS has yet to be 
tested.
    Piedmont Airlines also points out that most CFIT accidents with 
GPWS equipped airplanes occurred in foreign territory and that due to 
their limited flying range, U.S. part 121 turboprop airplanes do not 
operate abroad. Piedmont Airlines asks the FAA to issue a supplemental 
notice of proposed rulemaking (SNPRM) to address turboprop airplanes 
separately.
    The FAA agrees that the accident history data does not conclusively 
prove that the currently mandated GPWS is not effective in resolving 
the problem of CFIT accidents. However, the FAA has determined through 
the Volpe part 121 study that TAWS would have prevented CFIT accidents 
that current generation GPWS did not prevent. Due to the continued CFIT 
risk exposure with GPWS, the FAA is requiring TAWS.
    The FAA acknowledges that the majority of CFIT accidents have 
occurred in foreign territory. However, a significant number of CFIT 
accidents still occur in the U.S. with turboprop airplanes equipped 
with GPWS. In regards to the commenter's assertion that U.S.-registered 
part 121 airplanes have a limited flying range, the FAA notes that many 
operators are located near and fly into foreign territory where CFIT 
accidents have occurred; e.g., Canada, Mexico, and the Caribbean. The 
commenters have not provided any information to substantiate the need 
to further delay this action and there is no reason to believe new 
information would be obtained through publication of a supplemental 
notice.

Applicability to Reciprocating-Powered Airplanes

    The FAA proposed that the rule apply only to turbine-powered 
airplanes. Additionally, the FAA specifically requested comments on 
whether it

[[Page 16740]]

should require the installation of TAWS on reciprocating engine-powered 
airplanes.
    The General Aviation Manufacturers Association (GAMA) is against 
requiring TAWS on reciprocating-powered airplanes because the costs 
would be high (e.g., ``TAWS equipment would cost more than the hull 
value of the aircraft''), and the panel space for installing TAWS with 
a situational display is not available in these airplanes.
    The FAA did not receive any comments that would justify undertaking 
a new rulemaking project to mandate TAWS for reciprocating-powered 
airplanes.
    However, regarding the issue of panel space, the FAA knows of at 
least one manufacturer who has developed a complete TAWS unit that was 
designed to replace an existing panel instrument.

Applicability to Foreign-Registered Airplanes

    The Aerospace Industries Association (AIA) says that the language 
under proposed Sec. 91.223 makes reference only to U.S.-registered 
airplanes and provides an unstated exemption for airplanes of foreign 
registry. The AIA says that the proposed rule does not address those 
cases where ``the production process requires that manufacturers 
operate production airplanes that have been issued a Standard 
Certificate of Airworthiness.'' The AIA adds that, ``while at this time 
the equipment is not of U.S. nor foreign registry the manufacturer 
would appear to be in violation of FAR Part 91 requirements during the 
production process if terrain awareness and warning systems have not 
been installed.'' The AIA says that the rule language should be changed 
to address this issue.
    The Independent Pilots Association (IPA) recommends that TAWS be a 
uniform requirement for all airplanes over which the FAA has 
jurisdiction and not exclude foreign-registered airplanes operating in 
the United States.
    The FAA's response to these comments is that the FAA is addressing 
requirements for foreign-registered airplanes through the ICAO process, 
which may result in all nations adopting the TAWS standard. Regarding 
AIA's comment about airplanes that have been operating under a standard 
airworthiness certificate prior to foreign registry, the FAA does not 
agree that there is a problem here. The majority of the manufacturers 
are including TAWS as standard equipment in new production models. 
Also, there are rules that the FAA has in place for ferrying airplanes 
to foreign countries that would allow for airplanes being exported that 
do not meet U.S. requirements.

Comments to NTSB Recommendations

    The NTSB states that the NPRM is responsive to recommendations A-
95-35 and A-96-101 by proposing that TAWS be installed on all turbine-
powered airplanes with 6 or more passenger seats. If implemented, the 
NTSB contends that the rule will ``have a positive affect on aviation 
safety by reducing the opportunities for CFIT accidents.''
    The NBAA comments on NTSB recommendations A-92-55 and A-95-35, 
which recommended that all turbojet powered airplanes with six or more 
passenger seats have an operating GPWS system installed. The NBAA 
states that these recommendations are flawed, because the accidents 
prompting these recommendations were due to many contributing factors 
(a high-speed unstable approach, minimally experienced crew, fuel 
shortage, marginal weather conditions, low visibility). The NBAA does 
not believe TAWS equipment could have prevented these accidents.
    The FAA is confident in both the validity of the Volpe part 91 
study and its conclusion that the accidents could have been avoided if 
the airplanes had been equipped with TAWS. As described in the NPRM, a 
CFIT accident occurs when a properly functioning airplane under the 
control of a fully qualified and certificated crew is flown into 
terrain (or water or obstacles) with no apparent awareness on the part 
of the crew. By the nature of this definition, it is obvious that there 
had to be other contributing factors causing the crew to lose 
situational awareness, otherwise there would not have been a crash. 
However, the other contributing factors do not include airplane 
malfunctions or incapacitated crew; they generally include situations 
such as low visibility, inclement weather conditions, and being lost. 
The TAWS caution alert would have given the crew sufficient time to 
analyze the situation, then take corrective action. Finally, the 
warning alert to ``pull up'' would have allowed the crew to gain 
altitude and avoid hitting the terrain.
    The GAMA says that NTSB recommendations A-92-55 and A-95-35 only 
recommended GPWS (not TAWS) on turbojet airplanes (not turboprop 
airplanes). The USPA points out that NTSB has never issued a 
recommendation to require GPWS or TAWS on part 91 turboprops. The USPA 
further asserts that the FAA proposal appears to use the NTSB 
recommendation A-95-35 as the basis for including part 91 turboprops in 
the NPRM. The commenter further asserts that NTSB recommendation A-96-
101 would require EGPWS on transport category airplanes (not on general 
aviation part 91 airplanes). Similar comments were made by AOPA.
    GAMA is correct in saying that the NTSB recommendations A-92-55 and 
A-95-35 did not refer specifically to TAWS nor to turboprop airplanes. 
The NTSB has recommended since then that all turbine-powered airplanes 
with six or more seats be equipped with an EGPWS or an TAWS (A-99-36). 
The FAA's decision to require TAWS instead of GPWS and to include 
turboprops are for the reasons already discussed in the preamble. The 
reasons are briefly restated here. At the time the NTSB prepared and 
issued its earlier recommendations, TAWS did not exist. In response to 
the earlier NTSB recommendations, the FAA commissioned Volpe to do a 
study to evaluate the effectiveness of GPWS on smaller airplanes 
operated strictly under part 91. After the FAA certificated TAWS, the 
FAA expanded the Volpe study to also evaluate TAWS and compare the 
effectiveness of TAWS and GPWS. This study convinced the FAA that TAWS 
is superior to GPWS in eliminating CFIT. In addition, a cost benefit 
analysis showed that TAWS did indeed provide a significant benefit to 
aviation safety. Furthermore, 33 of the 44 CFIT accidents analyzed in 
the Volpe part 91 study involved turboprop airplanes. This high rate of 
CFIT accidents involving turboprop airplanes confirm the results of 
earlier studies conducted by the FAA.

NPRM Accident Analysis

    A number of part 91 and some part 135 operators say that GPWS/TAWS 
would do little to improve safety for their operations, and therefore 
is not worth the cost. Some of these commenters say that there is 
little factual data supporting the need for this equipment in their 
operations.
    The RAA and USPA question the legitimacy and validity of the Volpe 
part 121/135 study and find the Volpe part 91 study inconclusive. These 
commenters say that, of the 44 accidents analyzed in the Volpe part 91 
study, only 9 accidents may have been preventable using only EGPWS. The 
RAA believes the common causal link is the failure of the flight crews 
to follow procedures. The RAA believes that the accidents examined in 
the Volpe part 121/135 study should be more correctly categorized as 
``approach and landing,''

[[Page 16741]]

many of them affected by weather conditions.
    The USPA believes there are major flaws in the Volpe part 91 study. 
Among the probable causes listed for the accidents studied by NTSB are 
improper planning/decisionmaking, improper IFR/VFR procedures, failure 
to execute missed approach procedures, continuation of VFR flight into 
instrument meteorological conditions (IMC), poor crew coordination, and 
failure to establish proper climb rate. Similarly, another commenter 
says that the Dulles, Virginia, and Rome, Georgia, accidents cited in 
the Volpe part 91 study were not the result of a CFIT, rather they were 
due to such factors as inexperienced crew, low visibility, and an 
unstable approach.
    The NBAA also analyzed the same accidents studied by Volpe (1985-
1994) and found only six accidents involving part 91 turbine-powered 
airplanes (not 44 accidents, as cited in the NPRM) that could have been 
related to CFIT. The NBAA found that most of these accidents were due 
to other factors, including improper or missed approach procedures, 
intentional descent below minimums, continued operations in below 
minimum weather, and VFR flight into IMC. The AOPA adds that ``little 
is known about crew procedures, their mental state, and if the crew's 
actions would have been timely and accurate enough to avoid the 
accident once they responded to warnings estimated to be provided by 
the proposed TAWS equipment in that scenario.''
    In addition, NBAA studied turbine-powered airplane CFIT accidents 
from 1966-1997 and found a total of 34 accidents involving part 91 
airplanes. These NBAA findings are also cited by GAMA.
    In response to comments made by NBAA, USPA, RAA, AOPA, and others 
that the accidents cited in the Volpe part 91 study were not the result 
of a CFIT, but were due to other factors such as poor crew 
coordination, the FAA disagrees. No accidents are caused by one single 
element. Under the FAA's definition of CFIT, these were CFIT accidents, 
have been designated as CFIT by the NTSB, and thus formed the basis for 
the NTSB's recommendations.
    The RAA also comments on the Volpe part 91 study's statement 
regarding 6 of the 9 CFIT accidents under part 91: ``since airplane's 
gears and flaps were in landing condition, the Mode 4 warning of GPWS 
would have been desensitized.'' RAA states that ``the procedure used in 
regional/commuter operations is to not commit to landing flaps until 
the field is in sight, so we believe that the Volpe study should have 
completed their geometric analysis on these six accidents as well, in 
order to determine whether there would have been a significant 
difference in pilot response time'' between GPWS and TAWS.
    The RAA believes that the FAA needs to determine whether the use of 
TAWS will lead to more approach and landing accidents that are 
characterized by the pilot's failure to adequately evaluate inflight 
weather conditions, failure to maintain sufficient altitude during the 
approach to land, etc.
    In response to RAA's comments about the Volpe part 91 study, the 
FAA's position is that the Volpe part 91 study was done specifically to 
determine the effectiveness of TAWS, because that was the system the 
FAA was considering. The intent of the Volpe part 91 study was for the 
FAA to determine if TAWS was technically feasible. GPWS is a system 
using 1970's technology that has reached the limit of its usefulness. 
The FAA believes more modern technology is needed to gain more accident 
prevention potential to eliminate CFIT's. In the past the FAA has 
chosen not to require GPWS on airplanes operated under part 91 because 
of its technical limitations and costs. TAWS solves those limitations 
and has potential for future enhancements with lower cost for airplanes 
already equipped with GPWS.
    In addition, the purpose of the Volpe part 91 study was to confirm 
that the TAWS system was superior to GPWS in eliminating CFIT. In fact, 
in the part 91 study the GPWS system used for comparison purposes was 
the most advanced GPWS system. In reality many of the GPWS systems in 
service are the older versions that have been plagued with nuisance and 
false alarms.
    Similarly, GAMA references another study done outside of this 
rulemaking and refers to it as a second Volpe part 91 study. That study 
is dated July 1997, and examined all CFIT general aviation accidents 
(1983-1994) and concluded that CFIT is a small percentage of general 
aviation accidents. The GAMA says that the study showed 121 CFIT 
accidents in 1991, but that by 1994, such CFIT accidents had decreased 
to 68, which represented only 3.7% of all general aviation accidents.
    In response to GAMA's comment that the second Volpe part 91 study 
concluded that CFIT is a small percentage of general aviation 
accidents, the same report also shows that the small percentage (3.7%) 
of accidents represents 17% of all fatalities and that accidents caused 
by CFIT and spins are the leading causes of general aviation 
fatalities. Furthermore, the FAA's cost-benefit analysis of TAWS 
equipment used for general aviation operations showed that TAWS did 
indeed provide a significant benefit to general aviation safety.
    Some commenters state that the accident statistics provided in the 
NPRM do not justify requiring TAWS on turboprop airplanes. One-
commenter points out that the NPRM says that TAWS will only avert 2.3 
accidents per million flight hours in a 6-9 seat turboprop airplane. 
This commenter believes that this small number is justification for 
exempting this category of airplane from the TAWS rule. This commenter 
also comments that the Volpe part 91 study (table 10) said that 6 of 
the 33 turboprop accidents could have been prevented with TAWS. This 
commenter says that ``5 of the 6 accidents involved aircraft on 
approach to landing. These accidents resulted from pilot error in being 
too low on glideslope, or descending below MDA.''
    As an example of the effectiveness of the current rule, Allied 
Signal cites differences in accident statistics between turboprops 
fitted with GPWS and turboprops without GPWS. After GPWS was required 
for part 135 turboprop operations, there was an estimated 20-to 30-
times reduction in CFIT risk. Allied Signal further states that the 
results of the Volpe studies on the predicted effectiveness of TAWS 
correlate well with its own independent analysis.
    In response to the comment that says that TAWS is not justified 
because it would avert only 2.3 accidents per million flight hours, the 
FAA emphasizes that its mission is to save lives. Studies show that 
TAWS does indeed save lives, is cost effective, and contributes 
significantly to general aviation safety.
    The NATA and other operators comment that the nine CFIT accidents 
analyzed in the Volpe part 121/135 study did not include any airplanes 
with fewer than ten passenger seats conducted by part 135 on-demand air 
charter operators. The NATA says that these operations differ from 
scheduled operations, for example, airplanes with fewer than nine seats 
conduct few international operations where CFIT accidents are likely to 
occur. Therefore, TAWS should not be required for on-demand part 135 
operations ``until such time as a convincing and thorough data-based 
review is conducted with associated cost/benefit analysis.''
    The NATA and others are correct in their assertions that the Volpe 
part 121/135 study did not include airplanes with fewer than ten 
passenger seats in

[[Page 16742]]

part 135 operations. The study was conducted to determine the 
feasibility of retrofitting GPWS with TAWS. Currently, GPWS is not 
required for airplanes operated under part 135 with fewer than ten 
seats. The Volpe part 91 study shows compelling evidence supporting the 
use of TAWS, and the FAA has determined that the same types of 
airplanes are often operated under both parts 91 and 135. Therefore, 
the FAA is unable to justify setting a different standard based solely 
on the type of operation. The part 91 rule applies to all airplanes, 
including those operated under parts 121 and 135. The FAA is amending 
parts 121 and 135 to make it clear that airplanes operated under these 
parts will be required to replace current GPWS equipment with TAWS 
equipment. The Volpe part 91 study was conducted to consider 
installation of current GPWS or EGPWS on all part 91 turbine-powered 
airplanes of 6 or more passenger seats. The study concluded that GPWS 
could have avoided 33 of the 44 (75%) accidents and 96 fatalities, and 
EGPWS could have avoided 42 of the 44 (95%) accidents and 126 
fatalities. These conclusions justify use of TAWS on all airplanes of 6 
or more passenger seats.
    In response to NATA's comment concerning the use of TAWS on 
airplanes used in part 135 on-demand operations, the FAA points out 
that the Volpe part 121/135 study was never intended to look at part 
135 scheduled versus part 135 on-demand operations. The study was 
conducted to determine the effectiveness of TAWS on any airplane type, 
not the effectiveness in regard to the type of operation.

Comments on Costs of TAWS

    Many commenters, including the Air Transport Association (ATA), 
RAA, USPA, Raytheon, Continental Airlines, and Aloha Airlines say that 
the NPRM's analysis vastly underestimates the installation, retrofit, 
and maintenance costs associated with GPWS and TAWS. They say that 
these costs would be prohibitive for part 91 and part 135 operators. 
Raytheon and USPA suggest that retrofit cost estimates would exceed the 
value of the small turbine-powered airplanes and would force 
unnecessary retirement of the airplanes. Some operators specifically 
address retrofit costs and state that their airplanes are not 
configured to be easily equipped with GPWS/TAWS equipment without major 
expense.
    The RAA and USPA believe the FAA's cost estimates for complete TAWS 
installation are extremely low. Using GAMA avionics figures, these 
commenters estimate the installation of a TAWS on in-service turboprop 
airplanes used in parachute operations will range between $66,020 and 
$96,828, mostly because they lack the necessary prerequisite equipment.
    The GAMA's comment included a cost analysis for part 91 newly 
manufactured and in-service turboprops and turbojets. The GAMA 
estimates the costs to install TAWS would be much higher than those 
estimated by the FAA. The following estimates were provided: (1) For 
newly manufactured turboprops, the range would be $24,600 to $108,163, 
depending on the additional equipage needed to meet TAWS; for existing 
turboprops, the range would be $34,600 to $141,163, depending on 
existing equipage; (2) For newly manufactured turbojets, the range 
would be $24,600 to $69,985, depending on equipage; for existing 
turbojets, the range would be $34,600 to $141,163, depending on 
equipage.
    The NBAA and AOPA support GAMA's findings that TAWS costs would 
have a wide range, depending on the type of airplane operated. The NBAA 
also says that it was quoted, from an avionics repair station, an 
average cost of $105,000 for equipment, labor, installation, testing, 
and certification. The NBAA recommends that the FAA perform a new cost/
benefit analysis which would include not only TAWS equipment, but the 
costs of system modifications necessary to accommodate TAWS, 
installation, labor, testing, and certification.
    The HAI and other operators support the AACA's assertions that the 
FAA's cost projections for TAWS (purchase, installation, maintenance, 
and training) are significantly understated. The HAI says that the 
FAA's underestimation of costs, as well as its overestimation of safety 
benefits, echoes other recent rulemaking actions that affected the 
rotorcraft industry, including recent NPRM's on Digital Flight Data 
Recorders (DFDR) (61 FR 37144, July 16, 1996) and Type Certification 
Procedures for Changed Products (62 FR 24287, May 2, 1997).
    The FAA acknowledges the cost to install TAWS and retrofit 
airplanes with TAWS is higher than originally estimated. The cost would 
be more burdensome for part 91 and some part 135 operators. The final 
rule provides relief to these operators. The FAA has changed TSO-C151 
to include two acceptable classes of equipment. Class A equipment will 
be required for airplanes operated under part 121 and part 135 of 10 or 
more passenger seats; this class of equipment will be the same as 
originally proposed. Class B equipment will be required for airplanes 
operated under part 91 with 6 or more passenger seats and airplanes 
operated under part 135 with 6-9 passenger seats. Class B equipment 
includes basic TAWS safety features. The purchase and installation of 
Class B equipment reduces the costs to operators of airplanes operated 
under part 91 with 6 or more passenger seats and airplanes operated 
under part 135 with 6-9 passenger seats. In addition, the process of 
obtaining supplemental type certificates (STC's) will be greatly 
expedited. Unlike Class A equipment, Class B does not entail extensive 
installation procedures because it is not integrated with numerous 
airplane systems.
    This final rule requires the use of Class A equipment on airplanes 
operated under part 121 and airplanes with ten or more passenger seats 
operated under part 135. The FAA made this decision for the following 
reasons. First, Class A equipment includes the functions of GPWS. The 
existing FAA and ICAO requirements are that these airplanes must 
install GPWS. The TAWS functions are in an addition to and separate 
from GPWS. Both TAWS and GPWS requirements are included in TSO-C151. 
Therefore, this rule does not eliminate the GPWS requirement. The ICAO, 
while also requiring TAWS, is also maintaining its GPWS requirements. 
The use of GPWS is a proven concept with over 20 years of preventing 
many CFIT accidents; however, the FAA is requiring TAWS to further 
reduce the number of CFIT accidents. Second, these airplanes also are 
required to carry windshear protection devices. Manufacturers have 
built the windshear protection into the GPWS equipment and are doing 
the same with the TAWS Class A equipment. Third, Class A equipment is 
packaged in a standard avionics box to fit into the avionics bay of 
these larger airplanes. Fourth, Class A equipment box is designed to 
meet the more rigorous requirements for electrical and electronic 
equipment such as 14 CFR sections 25.1301, 25.1309, 25.1321, 25.1351, 
25.1353 and 25.1431. Fifth, Class A equipment is designed to be 
compatible with and to be integrated into other airplane systems 
typically found on large, commercial airplanes such as autopliot, 
flight management system, data bus, weather radar, flaps indicator, 
landing gear indicator, and instrument landing system glideslope.
    This final rule requires, as a minimum, Class B equipment for 
airplanes operated under part 91 and airplanes with six to nine 
passenger seats operated under part 135. Class B equipment contains 
only TAWS functions, i.e. the comparison of the

[[Page 16743]]

airplane's current position information to an onboard database. It is a 
very basic piece of equipment, packaged in a small box that can be 
placed almost anywhere in a small airplane where there is available 
space. It is designed to provide protection from CFIT accidents for 
airplanes that currently do not have such protection. These airplanes 
never had a requirement for GPWS and in the NPRM the FAA proposed 
requiring GPWS and TAWS but decided in the final rule to require only 
TAWS. The Class B equipment is designed as a less costly, small device 
for airplanes that do not have much space and for airplanes that may 
not be compatible with Class A equipment. The operators of these 
airplanes may install Class A equipment if they desire. In fact, one 
manufacturer of TAWS equipment has informed the FAA that operators of 
large airplanes operating under part 91 voluntarily are installing 
Class A equipment because of the features and benefits of GPWS. 
Operators of airplanes required to install Class A equipment do not 
have the option of installing Class B equipment because the Class B 
equipment does not contain the required GPWS functions.
    GAMA also comments that the FAA underestimated the production of 
new general aviation turbine-powered airplanes. GAMA says that ``in 
domestic production alone, American manufacturers of general aviation 
airplanes have already reported to GAMA deliveries of 282 new jets and 
162 new turboprops through the third quarter of 1998.''
    One commenter, a part 91 turboprop operator, says that GPWS costs 
would constitute about 10% of the value of his airplanes. This 
commenter recommends that, if mandated, the rule should be on a 5 to 10 
year time line so that more GPWS systems will be produced and they will 
become cheaper.
    A part 91 operator points out that the costs associated with 
installing TAWS could result in more accidents because some operators 
would sell their turboprops and fly piston airplanes. This commenter 
says that these airplanes ``are not as reliable, but can carry more 
passengers, are cheaper to operate, and will not be required to have 
TAWS.''
    In response to the comment that some operators of existing 
turboprop airplanes would switch to piston-engine airplanes because 
piston-engine airplanes will not be required to have TAWS, it is not 
the intention of the FAA to put an undue financial burden on owners/
operators of small turboprop airplanes nor to cause them to take such 
drastic action. Therefore, as described above, the FAA is amending 
proposed Secs. 91.233(b) and 135.154(b) `` both having to do with 
existing planes `` by allowing part 91 operators of airplanes with 6 or 
more passenger seats and part 135 operators of airplanes with 6-9 
passenger seats to meet different TAWS requirements.
    The NATA contends that the FAA has failed to provide an accurate 
picture of the equipment and installation costs for part 135 on-demand 
air charter operations. The NATA points out that the discounted prices 
used in the NPRM (for 10 or more units) would not apply to most part 
135 on-demand air charter operations since they typically operate a 
small number of airplanes. The NATA adds that the FAA fails to 
adequately cover other costs including wiring/installation kits, radar 
altimeters, other instruments needed to communicate with TAWS, airplane 
downtime during installation, and installation labor costs. The NATA 
says that the above factors would result in an average TAWS cost of 
$100,000 per airplane for part 135 on-demand charter operations.
    The United States Air Tour Association (USATA) comments that, in 
order to comply with the existing rule, its members purchased and 
installed GPWS equipment in their airplane fleets at a cost of more 
than $41,000 per airplane. This substantial capital investment by USATA 
members was made in spite of the fact that most of the airplanes are 
used in day VFR sightseeing applications. A TAWS requirement would 
require USATA members to essentially scrap their recent investments. 
USATA does not believe the TAWS retrofit is justified, given the GPWS 
safety record.
    In response to USATA, by the time operators have to comply with 
this final rule, the 10-year amortization of the cost of the GPWS 
system will be completed.
    Some commenters state that GPWS will not have a large trade-in 
value once TAWS becomes a requirement for all airplane markets for 
which a GPWS might be used.
    In response to the comment regarding trade-in values, the FAA 
stands by its use of trade-in value in the regulatory evaluation. The 
FAA was again advised by the manufacturer that it would give trade-in 
value against the purchase of TAWS. Other manufacturers may also offer 
trade-in credits.
    An Alaska-based operator adds that the Unfunded Mandates Act of 
1995, which requires that the FAA assess the impact of regulatory 
changes on state, local, and tribal governments, has not been 
adequately addressed. The commenter says that the requirements of the 
Act were not adhered to in the commuter rule when many carriers had 
voiced concern that they would not be able to bear the economic burden 
of that rule. The commenter believes that the ``requirements associated 
with this proposed rule will cause history to repeat itself in Alaska, 
thereby causing further disadvantage to the traveling public.''
    The costs of the final rule does not equal $100 million in any one 
year due to changes that have taken place since the proposal. Some of 
those changes are (1) The final rule is not applicable to certain 
segments such as parachute, aerial and firefighting operations, (2) The 
allowance of lower cost TAWS equipment with equivalent safety and (3) 
The decision by a significant proportion of manufactures/operators to 
voluntarily equip airplanes with TAWS. Consequently, the Unfunded 
Mandates Reform Act does not apply to this rule.

GPWS/TAWS Technology

    The AIA comments on the section in the NPRM under ``VNTSC 
Conclusion'', which states that ``The study emphasized that the CFIT 
accident prevention in all cases would have resulted not so much from 
increased warning durations following system detection of terrain 
threats, as from the fact that flight crews, given a continuous terrain 
display, would have perceived these terrain threats and responded to 
them well before EGPWS was required to generate warnings.'' The AIA 
comments that Boeing would object to a change in the GPWS intended 
function, and adds that the NPRM assumes that a flight crew would want 
to have terrain data continuously displayed.
    In response to AIA's comment about a continuous terrain display, 
the FAA previously pointed out that the Volpe part 121/135 study stated 
that the continuous terrain display feature of EGPWS may be even more 
important than the terrain threat detection/alert/warning features in 
breaking the chain of decisions leading to CFIT. Flight crews lacking 
an outside visual perspective are given an internal continuous display 
of nearby terrain, greatly heightening situational awareness. Rather 
than a last ditch warning of imminent danger, the continuous terrain 
display would allow crews to maneuver to avoid terrain long before it 
ever becomes an obstruction to their flight path. TAWS represents a 
pivotal advance in providing flight crew terrain awareness. Thus, the 
FAA has determined that the terrain situation awareness display is a 
valuable function, and is requiring its use for all part 121 operations 
and for those part 135 operations conducted with

[[Page 16744]]

airplanes configured with 10 or more passenger seats. However, the FAA 
recognizes that in accomplishing normal piloting duties, the flight 
crew should not continuously stare at the terrain display. In addition, 
the display may be used for other information such as weather. The FAA 
therefore is not requiring the continuous use of the display.
    The AIA also recommends that the preamble language under 
``Functions of TAWS,'' ``Terrain Clearance Floor,'' should be changed 
to read ``The terrain clearance floor creates an increasing terrain 
clearance envelope around the closest (not ``intended'') airport runway 
related to the distance from the runway * * *'' The AIA says that the 
NPRM language assumes that the closest runway is the intended runway, 
and that ``EGPWS has no way of knowing what the ``intended'' (i.e. 
destination) airport would be unless significant design changes were 
made.
    In response to AIA's comment about the terrain clearance floor 
feature, the FAA agrees that, concerning one manufacturer's TAWS, the 
commenter is correct; the closest runway is not always the intended 
runway and on a landing approach when flying by a nearby unintended 
runway, the TAWS may temporarily build a terrain clearance envelope 
around the unintended runway. However, the FAA does not see this as a 
problem for four reasons. First, the TAWS will, in sufficient time, 
switch the terrain clearance floor to the intended runway as soon as it 
becomes the closest. Second, if the envelope around the unintended 
runway gives off an alert, this is an indication that the plane is 
obviously too close to terrain related to the unintended runway. Three, 
the clearance floor is not displayed so there would be no confusing 
information presented to the flight crew. Finally, not all TAWS systems 
have this method of operation.
    The NBAA and GAMA say that there could be difficulty in integrating 
TAWS, (which is a digitally based piece of hardware) into the many 
airplanes that use analog-based systems. The GAMA and AOPA say that 
other systems required by TAWS include the air data computer, radar 
altimeter, global positioning system, as well as four annunciators 
(alarms) and a display for the information. The NBAA says that ``it is 
unclear whether all of the modifications necessary to adapt such an 
advanced piece of hardware into a legacy avionics suite will result in 
a fully functional TAWS system.'' The NBAA, GAMA, and AOPA say that 
these integration difficulties would greatly affect the cost estimates 
for purchase, installation, and approval of TAWS.
    Regarding comments by NBAA and GAMA about integrating TAWS into 
airplanes with analog based systems, the FAA is aware that 
manufacturers are designing digital and analog TAWS models. Thus, there 
should be an appropriate model for each airplane's existing 
configuration.
    Some commenters, including a part 91 charter operation, say that 
current GPWS technology still presents the problem of false warnings, 
causing pilots to disregard these warnings (e.g., when descending to an 
airport). One commenter says that GPWS technology should be further 
developed to insure that these kinds of problems are eliminated, and 
that the FAA should postpone this rule until the technology is 
improved.
    In response to the commenters who says that false warnings are 
still a problem and the commenter who requested that the FAA postpone 
this rule until GPWS technology is improved, the FAA's position is that 
the proposed rule recognized the false warning problem in existing 
GPWS. As stated in the NPRM, GPWS equipment has been improved since it 
was first required in the 1970's. These advances include improvements 
in terrain detection logic that provides increased terrain warning 
durations in the order of 10-15 seconds on average, resulting in 
additional time for the pilot to maneuver that can be crucial in 
preventing accidents. In addition, the NTSB also recognized and 
addressed this issue by recommending to the FAA that early generation 
GPWS equipment be upgraded (NTSB recommendations A-92-39 through A-92-
42). The final rule implements these NTSB recommendations to retrofit 
all GPWS with TAWS.
    Another commenter responds to the FAA's statement in the NPRM that 
it ``expects that manufacturers will provide (an alert) at least 20 
seconds in advance of a potential impact.'' This commenter says that 
TAWS should provide a first alert of not less than 30 seconds prior to 
potential impact.
    Regarding the comment about the TAWS alert time, the FAA addresses 
alert times in the TSO document. However, for clarity, the FAA restates 
the following concerning alert times from the NPRM:
    ``The function of the new proposed TAWS standard is to prevent CFIT 
by providing alerting times earlier than those provided by existing 
ground proximity warning systems manufactured in accordance with 
Technical Standard Order (TSO)-C92c. Typically GPWS aural and visual 
warnings occur about 20 seconds or less before potential impact with 
terrain. The visual warning is usually a blinking light and the aural 
warning is usually a message through the airplane's audio system.
    ``Studies indicate that average combined pilot and aircraft 
reaction time to avoid a CFIT after warning is within the 12 to 15 
second range. The FAA has approved for installation a TAWS (the EGPWS) 
that provides an initial alert approximately 60 seconds before 
potential impact and another alert about 30 seconds before potential 
impact. These alerts are both aural and visual. These alerting times 
were based on data from actual CFIT accidents and were chosen by the 
manufacturer as the best compromise to provide timely alerts while 
still minimizing nuisance alarms. Human factors research and FAA 
experience show that, if an aural cockpit alarm sounds too often as a 
false alarm, the flight crew will either begin to ignore it or will be 
tempted to disable the system. Therefore, while the forward looking 
capability of TAWS could provide an alert far in advance of potential 
impact, the alerting time must be as short as possible, while still 
allowing an adequate time to avoid impact. The FAA will carefully 
evaluate the alerting times for each proposed TAWS, but expects that 
manufacturers will provide at least 20 seconds in advance of a 
potential impact.''
    The NTSB comments that standards for TAWS design should be 
developed to minimize the potential for misuse of the equipment. The 
NTSB says that the FAA alluded to this issue in the NPRM when it 
pointed to the possibility that pilots would be tempted to use TAWS for 
navigational purposes and that pilot training should be developed to 
prevent this occurrence. The NTSB states that pilot training should not 
be used to ``compensate for potential deficiencies in the TAWS 
design.'' The NTSB adds that the design of TAWS should ``reflect the 
results of a thorough human factors evaluation to obviate the need for 
training and other procedural requirements that compensate for design 
deficiencies or misuse of design principles.''
    In response to the NTSB's comment, the NPRM pointed out that the 
Volpe part 121/135 study recognized that the terrain display may 
present a new set of challenges to pilots. The TAWS's topographical map 
display could offer a temptation for pilots to use it for navigational 
purposes. Therefore, the FAA stated in the NPRM that pilot training 
should emphasize that other

[[Page 16745]]

airplane systems are intended for this purpose, and any TAWS terrain 
display features are intended only to provide terrain awareness, not 
for aerial navigation. (The NPRM also cited Notice N8110.64, Enhanced 
Ground Proximity Warning System, which provides guidance on EGPWS and 
specifies that Airplane Flight Manuals should state that EGPWS 
shouldn't be used for navigational purposes.)
    The Air Line Pilots Association (ALPA) strongly supports the NPRM's 
inclusion of the visual display of terrain as part of the overall TAWS 
system. The ALPA emphatically agrees with the Volpe part 121/135 study 
finding that the visual display is the most important function of the 
TAWS system because it provides flight crews with a picture of the 
surrounding terrain threat that can be responded to well before the 
system is required to generate warnings.
    The ALPA supports the need for the TAWS system to have a backup to 
the synthetic terrain data, such as radar altimeter inputs for 
generating warnings in the event of erroneous terrain database 
information or erroneous navigational inputs.
    The ALPA encourages the FAA to preclude delay of the final rule due 
to potential objections by part 91 operators. The ALPA feels the final 
rule should be applied to commercial operators as soon as possible in 
an effort to prevent future controlled-flight-into-terrain accidents.
    In response to ALPA's first comment that supports mandating a 
terrain situational awareness display, the FAA agrees that such a 
display is a very valuable tool and therefore will continue to mandate 
such a display for part 121 operators and part 135 operators of 
airplanes with 10 or more passenger seating. However, the FAA is 
revising the final rule to make such a display optional for part 91 
operators and part 135 operators of 6 to 9 passenger seating for the 
following reasons:
    While the display adds an additional level of safety to large 
commercial transports (and this is in line with the FAA policy of 
requiring a higher level of safety for such airplanes), the display 
itself does not save lives. Once in a potential CFIT situation, what 
saves lives is the TAWS caution alerts and warning commands. Requiring 
a display on a smaller, older airplane in some instances will present 
such an oppressive financial burden that the owner/operator may either 
go out of business or convert to a less safe piston-engine airplane. 
Furthermore, there is promising new technology such as moving maps that 
in the near future will provide inexpensive additional terrain 
situational awareness to these smaller, older airplanes.
    In response to ALPA's second comment to require a radar altimeter 
as a backup to the terrain database, the FAA is requiring TSO-C151 
Class A equipment for part 121 operators and part 135 operators of 10 
or more passenger seating and TSO-C151 Class B equipment for part 91 
operators and part 135 operators of 6 to 9 passenger seating. Class A 
equipment requires a radar altimeter; Class B equipment does not. The 
reasons behind this decision are the same as mentioned above concerning 
the terrain situational awareness display.
    In response to ALPA's third comment concerning not delaying the 
rule due to potential objections by part 91 operators by applying it to 
commercial operators as soon as possible, the FAA believes it is 
processing the rule as expeditiously as possible. The FAA further 
believes it can process the rule faster as currently defined and 
believes that redefining it at this time into two rules--one for 
commercial operators and one for part 91 operators--would actually 
delay its implementation.
    The ATA recommends that the final rule clearly state that TAWS 
systems installed before adoption be considered compliant, including 
those installed under FAA-approved Supplemental or Amended Type 
Certificates, Service Bulletins or JAA approvals. ATA adds that the 
final rule should clearly state whether systems without a color terrain 
display, certificated and installed prior to the final rule, would be 
in compliance.
    In response to ATA's first comment requesting that the FAA formally 
recognize as compliant TAWS systems installed before adoption of the 
final rule, the FAA recognizes and appreciates the significant 
voluntary action by ATA and its members as well as by other segments of 
the industry. It has been and still is the FAA's intention to recognize 
all FAA approved TAWS installations (i.e., those that meet the 
requirements of TSO-C151) done voluntarily before issuance of the rule 
as being in compliance with the rule.
    In response to ATA's second comment concerning a color display, the 
FAA believes that ATA misunderstands the display requirements. The FAA 
is not requiring only a color display; monochromatic displays have been 
allowed and will continue to be allowed. Therefore, the FAA sees no 
reason to reference this subject in the final rule.

TSO Comments

    When the FAA published the TAWS NPRM, it also made available a 
draft of a proposed Technical Standard Order (TSO)-C151, entitled 
Terrain Awareness and Warning System. The proposed TSO was made 
available under a separate Notice of Availability in the Federal 
Register on November 4, 1998 (63 FR 59494), which requested public 
comments on the TSO. All comments related to the TSO, whether in 
response to the NPRM or the TSO Notice of Availability, were given to 
an FAA technical team to evaluate and use in developing the final TSO.
    In response to the TSO notice of availability, commenters submitted 
a large number of suggested changes to the TSO. (The substance of these 
comments are discussed in the TSO disposition report.) In trying to be 
as flexible and as accommodating as technically feasible, the FAA 
accepted and included most of the suggested changes, and developed a 
revised version of the draft TSO. This proposed TSO was made available 
in a second notice of availability in the Federal Register on May 27, 
1999 (64 FR 28770), which again requested public comments on the TSO.
    Based on the above actions, the FAA issued a final version of TSO-
C151 on August 16, 1999. This TSO will be the means to obtain approval 
of TAWS products and is described below.
    TSO-C151 prescribes the minimum operational performance standards 
that TAWS equipment must meet to be identified with the TSO-C151 Class 
A or B marking. At present the TSO includes two classes of equipment: 
(1) Class A, intended for airplanes operated under part 121, and for 
airplanes of 10 or more passenger seating operated under part 135; and 
(2) Class B, intended for airplanes operated under part 91, and for 
airplanes of 6 to 9 passenger seating operated under part 135. TSO-C151 
does not require the use of specific design criteria nor prescribe the 
use of specific components. The applicant is free to design its own 
system providing it meets the minimum operational performance 
requirements of the TSO.
    Class B equipment includes basic TAWS safety features, such as: 
Forward looking terrain warnings; minimum ground clearance plane 
function; GPWS mode 1 (high descent rates), mode 3 (descents after 
takeoff), and mode 6 (the 500 foot voice callout). Optional TAWS 
features of Class B equipment include: radio altimeter; a landing gear 
position sensor input to TAWS; a flap position sensor input to TAWS; a 
glideslope

[[Page 16746]]

deviation input to TAWS; a flap override switch in the cockpit; a 
glideslope (mode 5) inhibit switch in the cockpit; a TAWS inhibit 
switch in the cockpit; a terrain display; and a weather/terrain 
switching function.
    TAWS technology, as well as other avionics technology, is advancing 
at a very rapid pace. Because of this, the FAA expects to revise TSO-
C151 periodically and amend the rule when necessary, to include other 
classes or subclasses as new technology is developed and proven. An 
example of a new class could be the addition of a Class C intended for 
piston-powered airplanes and turbine-powered airplanes of less than 6 
passenger seating. An example of a new subclass could be a Class B, 
level 1 that could include geometric calculation of altitude using GPS/
WAAS (Global Positioning System/Wide Area Augmentation System) when 
that system is operational. The FAA also realizes that technology may 
advance and prove itself faster than the FAA can keep TSO-C151 up to 
date. In these situations, the FAA will make use of the deviation 
process allowed under Sec. 21.609, Approval for Deviation. The FAA 
intends to provide maximum flexibility for industry to continuously 
develop more advanced and less expensive TAWS equipment.

Supplemental Type Certificates (STC's)

    The NATA says that the NPRM's estimate of 82 STC's for retrofitting 
the part 135 fleet with TAWS is low because in some cases, ``a single 
aircraft model, particularly older aircraft models, may have evolved to 
a point where the cockpit/avionics panel and currently installed 
equipment vary greatly. As a result of this variance, ``follow-ons'' 
may not be available for many airplanes and many more ``first of type'' 
installations will be required for Part 135.'' This could result in STC 
approval delays and could significantly impede timely equipment 
installations. Other commenters questioned the number of estimated 
STC's.

FAA Response

    The FAA disagrees with NATA's statement that there would be delays 
in STC approvals and equipment installations. When the FAA developed 
the compliance schedule, the FAA took into account the potential FAA 
STC approval workload. In addition manufacturers have obtained 
additional STC's since the NPRM was published and are making them 
available for their customers. Taking all this into consideration, the 
FAA has determined that the approval process will not hinder the 
implementation of this rule.

Training

    The FAA did not propose changes to existing training requirements. 
However recent new training requirements on crew resource management 
(CRM) for flight crewmembers should provide additional safeguards in 
conjunction with the use of TAWS. This requirement applies to flight 
crewmembers operating under parts 121 and 135 and took effect on March 
19, 1998. (60 FR 65940, December 20, 1995).
    The Independent Pilots Association (IPA) criticizes the FAA for not 
changing current training requirements to specifically require training 
in the use of TAWS. IPA believes that without specific training in what 
TAWS is designed to do and what it is not designed to do, the full 
safety benefits and risk reduction will not be realized.
    Alternatively, a number of commenters say that increased training 
for situational awareness and monitoring is needed, rather than 
``another expensive electronic box.''
    Raytheon points out that even in some of the part 121 CFIT 
accidents that involved airplanes that ``were new generation and well 
equipped with the latest in technology'', there was a loss of 
situational awareness by the flightcrew. Therefore, the best way for 
operators to reduce CFIT accident risk is through ``improved training, 
emphasis on standardization of procedures, and review of human 
factors.''

FAA Response

    The FAA agrees that training is an important element to minimizing 
CFIT and recommends a three-pronged approach: (1) Proper pilot 
training; (2) Better decision-making tools; (3) Electronic hardware to 
assist the pilot. TAWS addresses the electronic hardware issue. The 
FAA's position is that training alone has not been successful in 
reducing CFIT accidents; therefore the FAA believes that it is 
necessary to require TAWS.
    The fact that the final rule does not mention training does not 
mean that no TAWS training is required. Under existing Secs. 121.415 
and 135.293 certificate holders are required to insure that each 
crewmember is qualified in new equipment, procedures, and techniques, 
including modifications to airplanes. The effect of this requirement is 
that whenever an operator installs new equipment, part of the approval 
process for that equipment includes showing that crewmembers have been 
adequately trained to use the new equipment.
    In addition, although not directly related to training, the final 
rule requires that operators include in their Airplane Flight Manuals 
the appropriate procedures for operating and responding to the audio 
and visual warnings of TAWS. Existing Sec. 91.9 requires that the pilot 
operate the airplane in accordance with the approved flight manual.

Other Government/Industry Efforts

    The NBAA recommends that the FAA delay action on this rule until it 
receives a report from the Joint Safety Analysis Team (JSAT). The NBAA 
is participating on the workgroup teams to study several root causes of 
general aviation accidents, including CFIT. The NBAA says that the 
JSAT's recommendations may include more cost effective alternatives to 
TAWS. A similar comment is also made by GAMA, which is the industry co-
chair of the JSAT.
    Raytheon strongly recommends that the FAA further investigate the 
effectiveness of TAWS in general aviation operations and consider 
alternatives to TAWS better suited to the general aviation environment. 
Raytheon states that further investigations are also supported by the 
Joint Industry/FAA Team, Proposed Action Plan, ``Controlled Flight into 
Terrain (CFIT) Avoidance for General Aviation.'' The Joint Industry/FAA 
Team submitted five recommendations to the FAA for reducing CFIT 
accidents, including equipment enhancements, pilot education and 
improvement in decision making aids for pilots.
    Similarly, AOPA recommends that the FAA implement the 
recommendations made by the ``Controlled Flight Into Terrain (CFIT) 
Avoidance for General Aviation'' report (August 1998). This report was 
put forth by a joint industry/FAA team which was established to respond 
to the ``The White House Commission on Aviation Safety and Security'' 
recommendation regarding EGPWS in general aviation airplanes. The team 
had concluded that there are a number of causes of CFIT accidents and 
that these factors can be addressed ``in more affordable, practical, 
and effective solutions.'' AOPA states that these recommendations would 
lead to voluntary equipage and would be more effective in reducing CFIT 
accidents than would a mandate for TAWS.
    GAMA encourages voluntary equipage of TAWS on general aviation 
turbine-powered airplanes.

FAA Response

    In response to NBAA and GAMA comments that the FAA delay the rule 
until it receives a report from the Joint

[[Page 16747]]

Safety Analysis Team (JSAT), the FAA does not believe such a delay is 
necessary, warranted or wise; the report was completed in April 1999. 
The NBAA and GAMA are valuable participants on the team and GAMA is a 
co-chair of the general aviation section of JSAT (GA-JSAT). The FAA is 
the other co-chair and also is a major participant, and as such, the 
FAA is aware of all JSAT transactions and activities. The FAA is aware 
that the GA-JSAT is emphasizing training. The FAA agrees that training 
is important, but as discussed earlier, training by itself, 
unfortunately will not solve the CFIT problem. The pilot needs a 
technical aid. The limitation of training is profoundly illustrated in 
the transport area. Commercial pilots have access to the best training 
in the world, yet CFIT accidents are the leading cause of fatalities in 
commercial aviation worldwide. In fact, the Transport Section of JSAT, 
in recognizing the limitations of training, has made TAWS its primary 
intervention strategy. There currently is a successful, cost effective 
technical aid available--TAWS--and it is incumbent upon the FAA to 
require this technical aid as expeditiously as possible.
    Raytheon and AOPA make reference to another FAA sponsored activity 
and report, the joint FAA/industry team report titled ``Controlled 
Flight into Terrain (CFIT) Avoidance for General Aviation.'' This team 
was organized by the FAA to supplement the TAWS rulemaking activity, 
not to replace it. The TAWS rule applies to U.S.-registered, turbine-
powered airplanes of 6 or more passenger seating. The team was formed 
to investigate how to eliminate CFIT accidents in the remaining group 
of general aviation airplanes not covered by the proposed TAWS rule, 
specifically piston-powered airplanes regardless of number of passenger 
seats and other airplanes of less than 6 passenger seats. In preparing 
the report, the team became convinced that its recommendations could be 
applicable to all general aviation airplanes, not just the narrow group 
mentioned above, and stated this in its report. The FAA co-chaired the 
team and participated in its deliberations. The FAA supports the 
recommendations of the team and, in fact, is supporting and 
participating in all the recommendations. The FAA sees no conflict 
between this report and the TAWS rule. As mentioned in the discussion 
in the section addressing the TSO, the FAA is building in the 
flexibility to incorporate the new technologies identified in the 
report as those new technologies come on line. Therefore, in response 
to Raytheon's first comment that the FAA further investigate the 
effectiveness of TAWS, the FAA already is participating actively in 
ongoing CFIT research and investigations and will continue its 
participation. In the mean time, as mentioned in the FAA response 
concerning the JSAT report, there currently is a successful, cost 
effective technical aid available--TAWS--and it is incumbent upon the 
FAA to require this technical aid as expeditiously as possible.
    In response to Raytheon's second comment that the FAA consider 
alternatives to TAWS, the FAA believes that Raytheon misunderstands the 
concept of TAWS. TAWS is a technical aid to eliminate CFIT accidents 
and is one of several integrated approaches; the others include 
improved training, better decision making information and better 
weather information. The new technologies, discussed in the report 
referenced by Raytheon, when integrated properly into an airplane, 
would be a TAWS and would provide TAWS functions.
    In response to AOPA's first statement that the recommendations in 
the report would lead to voluntary equipage, the FAA recognizes the 
voluntary effort by industry. Unfortunately, many owners/operators do 
not take voluntary action, so the FAA must require them to take action.
    In response to AOPA's second comment that the recommendations in 
the report will result in a more effective means of reducing CFIT 
accidents than would a mandate for TAWS, the FAA believes that, like 
Raytheon, AOPA misunderstands TAWS. The FAA believes that the technical 
recommendations in the report will lead to better and less expensive 
TAWS equipment. Much of this equipment will be available well before 
the compliance due dates. But the FAA and industry cannot keep waiting 
for better and less expensive equipment. CFIT accidents are tied with 
spins as the leading cause of fatalities in general aviation in the 
United States. There currently is a successful, cost effective 
technical aid available--TAWS--and it is incumbent upon the FAA to 
require this technical aid as expeditiously as possible. Waiting to do 
more research and investigations, or not using all available means at 
our disposal, including the use of cost effective technical aids, while 
additional people die in CFIT accidents, would be a dereliction of 
duty.

Compliance Schedule

    The FAA proposed amending Secs. 121.360 and 135.153 to add an 
expiration date of four years after the effective date of the final 
rule for the use of current GPWS systems. Thereafter, compliance with 
those sections would not be allowed in lieu of the provisions amended 
herein.
    The FAA proposed that, beginning one year after the effective date 
of the final rule, U.S.-registered airplanes manufactured after that 
date be equipped with TAWS. The FAA also proposed that turbine-powered 
airplanes manufactured on or before that date be equipped with TAWS 
within four years after the effective date of the final rule.
    The NATA states that, since there is only one TAWS product 
available that would meet FAA approval, there should be a longer 
compliance period for non-part 121 operations. This, coupled with the 
likelihood of changes to the TSO (based on incoming comments) will have 
a direct impact on the ability of current and future TAWS manufacturers 
to develop and offer their products in the marketplace. For these 
reasons, NATA says that the FAA should provide a ten-year timetable for 
part 135 on-demand air charter operations.
    The NATA also states that, since the most significant safety 
benefits will occur with TAWS installation on part 121 airplanes, and 
since manufacturers will have limited production capabilities, the 
emphasis should be on supplying equipment to part 121 operations. Also, 
a longer timetable will allow ``natural market development to help 
alleviate product supply, installation, certification, and cost 
dilemmas through increased manufacturer competition and the ability to 
absorb the substantial costs over time.''
    The RAA requests the compliance period be extended to a five year 
period for all 30+ seat turboprop airplanes; a seven year period for 
all 10 to 29 passenger seat turboprop airplanes; and eight year period 
for all 6 to 9 passenger seat turboprop airplanes; and extended to 
December 20, 2010, for all non-transport category airplanes that are 
classified as Sec. 121.157(f) types that will be phased out of part 121 
operations on the same date.
    Likewise, Northwest Airlines requests that airplanes planned for 
retirement prior to 2008 be exempt from the final rule. This would 
allow Northwest to focus more on accelerated installation on airplanes 
in its long-term fleet plan.
    The ATA comments that a one-year effective date after publication 
of the

[[Page 16748]]

final rule is necessary to accommodate realistic lead times for the 
productions ramp-up for piece parts and kits. The ATA also recommends 
that the final rule clearly state that TAW systems installed before the 
adoption of the final rule will be considered compliant. A related 
issue is whether systems certificated and installed before the adoption 
of the final rule without a color terrain display would be in 
compliance with the rule.
    Trans World Airlines, in conjunction with ATA, believes that the 
NPRM public comment period should be connected to the TSO public 
comment period for complete project public comments.
    Japan Airlines comments that the effective date of the final rule 
should be fixed on the basis of the progress made in manufacturing and 
installing TAWS, with special attention given to retrofit issues, such 
as changing from analog to digital.

FAA Response

    In response to comments from NATA, RAA, ATA, and Japan Airlines, 
the FAA does not believe that the rule should be delayed. Since the 
proposed rule was published, several other manufacturers have developed 
TAWS. The initial manufacturer, in response to this competition, has 
already lowered the selling prices of its TAWS products and has 
developed several smaller, less expensive systems for older planes, 
both analog and digital.
    When the FAA initially developed the compliance schedule, it took 
into account the production capability of only one manufacturer and the 
anticipated certification workload for the FAA. Since then, additional 
manufacturers have been developing and making available additional 
products beyond what was anticipated. Furthermore, TAWS manufacturers 
and airframe manufacturers are obtaining STC's and making them 
available to customers who install TAWS, thereby reducing the 
anticipated FAA certification workload. When taking these two factors 
into consideration, the FAA is convinced that the initially proposed 
compliance schedule can easily be met.
    In response to Northwest Airline's comment about exempting 
airplanes planned for retirement, the FAA does not agree. The commenter 
has not provided adequate justification as to why these airplanes 
should be exempted. Although Northwest Airlines may intend to retire 
certain airplanes by 2008, there is no guarantee that this will happen. 
Further, even if Northwest does retire the airplanes, there is no 
guarantee that those airplanes will go out of service permanently. They 
may be sold and used by others and, therefore, will need TAWS 
protection.

Miscellaneous Comments

    A commenter recommends that each airplane be given a rating system 
that indicates that it has a GPWS on board. It would then be up to the 
passenger to decide whether or not to fly on that airplane.

FAA Response

    The FAA does not think such a rating system would be practical or 
workable. Given the complexity of all the equipment required on the 
airplane, it would be difficult to convey to a boarding passenger, how 
each piece of equipment contributes to the overall safety of the 
airplane.

Paperwork Reduction Act

    As required by the Paperwork Reduction Act of 1995 (44 U.S.C. 
3507(d)), the FAA has submitted a copy of these sections to the Office 
of Management and Budget for its review. The collection of information 
was approved and assigned OMB Control Number 2120-0631. This final rule 
requires a Terrain Awareness and Warning System for all U.S.-registered 
turbine-powered airplanes of 6 or more passenger seating. TAWS is a 
passive, electronic, safety device located in the avionics bay of the 
airplane. TAWS alerts pilots when there is terrain in the airplanes' 
flight path. Since there is not an actual collection of information, we 
cannot estimate a burden hour total and no comments were received on 
this information collection submission. However, for the purpose of 
controlling this submission, we will assign an one-hour burden to the 
package. There is a total cost estimate of 340 million dollars, for 
purchase and installation of the passive, electronic, safety device.
    An agency may not conduct or sponsor and a person is not required 
to respond to a collection of information unless it displays a 
currently valid Office of Management and Budget (OMB) control number.

International Compatibility

    The FAA has reviewed corresponding International Civil Aviation 
Organization international standards and recommended practices and 
Joint Aviation Authorities requirements. TAWS is a new system recently 
developed by American industry. The FAA intends to work through the 
ICAO process to harmonize this rule with the international community.

Regulatory Evaluation Summary

    Changes to Federal Regulations must undergo several economic 
analyses. First, Executive Order 12866 directs that each federal agency 
shall propose or adopt a regulation only upon a reasoned determination 
that the benefits of the intended regulation justify its costs. Second, 
the Regulatory Flexibility Act of 1980 requires agencies to analyze the 
economic effect of regulatory changes on small entities. Third, the 
Office of Management and Budget (OMB) directs agencies to assess the 
effect of regulatory changes on international trade. And fourth, Title 
II of the Unfunded Mandates Reform Act of 1995 requires each Federal 
agency, to the extent permitted by law, to prepare a written assessment 
of the effects of any Federal mandate in a proposed or final agency 
rule that may result in the expenditure by State, local, and tribal 
governments, in the aggregate, or by the private sector, of $100 
million in any one year. In conducting these analyses, the FAA has 
determined that this rule is ``a significant regulatory action'' under 
section 3(f) of Executive Order 12866 and, therefore, is subject to 
review by the Office of Management and Budget. This rule is considered 
significant under the regulatory policies and procedures of the 
Department of Transportation (44 FR 11034, February 26, 1979). This 
rule will have a significant impact on a substantial number of small 
entities, will not constitute a barrier to international trade, and 
does not contain a Federal intergovernmental or private sector mandate 
that exceeds $100 million in any one year.

Economic Evaluation

Introduction to Cost/benefit Analysis

    Since the publication of the NPRM, some important developments have 
occurred. The FAA received extensive cost information during the 
comment period (detailed information regarding the type of expenditures 
needed for specific airplane models and updated estimates of the size 
of the affected fleet) and developed alternatives to reduce costs while 
maintaining the increased level of safety expected from TAWS.
    In response to the commenters, the FAA has examined ways to reduce 
costs for smaller operators and still maintain the incremental level of 
safety provided by TAWS. The FAA has determined that a TAWS unit with 
significantly less complexity will meet desired safety objectives at 
lower cost for all part 91, and for certain operators under part 135. 
The savings to part 91 operators alone will be well over $200 million.

[[Page 16749]]

    The aviation industry has already moved to retrofit a large 
percentage of the existing fleet, and has placed orders that extend 
well into the future. The Air Transport Association (ATA) member 
airlines in particular have announced a voluntary program where they 
will equip their airplanes with TAWS. For domestic United States 
operators, there have already been nearly 4,500 TAWS deliveries. Over 
2,200 TAWS units ordered are backlogged. Nearly half of the airplanes 
operating under part 121 are already in compliance with this rule. 
Given that ATA member airlines voluntarily committed to retrofit their 
in-service fleet and to order new airplanes equipped with TAWS, a 
significant portion of incremental compliance costs (and equivalent 
associated benefits) for current part 121 airplanes and all future 
equipment delivered (i.e., future transport category airplanes) will 
not be counted in evaluating the regulatory impacts of this rulemaking.
    The incremental benefits and costs of the rule depend on several 
fleet related factors. To determine the affected fleet the analysis 
begins with the existing fleet, subtracts expected retirements, 
subtracts voluntary compliance, and adds future airplane deliveries 
that will be impacted by the rule.
    Estimates of lifecycle benefits were calculated on a per-airplane 
basis and summed over all affected airplanes to obtain an estimate of 
the expected fleet benefits. The calculations took into consideration 
passenger capacity, average load factors, proportion of fatalities 
given a CFIT accident, airplane value, and number of flight hours (see 
following discussion on part 121 for application of methodology).
    The estimate of benefits and costs for TAWS is for the overall 
rulemaking. However, since the benefit and cost impacts vary so widely 
across operators and equipment, specific equipment costs and both 
benefits and costs for parts 121, 135, and 91 were analyzed separately 
and are presented accordingly. The part 135 benefits discussion is more 
detailed than that of parts 91 and 121, given the re-evaluation of the 
part 135 accident data included in this final rule.

Part 121

    The FAA's database provides the estimate for the overall part 121 
fleet of 6,907 airplanes, which includes 5,362 turbojets and 1,545 
turboprops. The ATA membership fleet of 4,569 airplanes accounts for 
slightly more than 85 percent of the part 121 jet fleet. The ATA and 
the Regional Airline Association (RAA) provided the in-service part 121 
fleet expense by equipment type incorporated in this analysis.
    The FAA obtained information on the deliveries and orders for TAWS 
from AlliedSignal. As of May 31, 1999, AlliedSignal had delivered 2,881 
TAWS units to United States domestic operators of part 121 passenger 
and cargo airplanes and to original equipment manufacturers (OEMs). The 
FAA reduced the OEMs' deliveries by fifty percent (to account for 
overseas sales) as a rough estimate of U.S. new equipment deliveries 
with TAWS units installed. For AlliedSignal's domestic backlog, the FAA 
included all operators' orders and excluded all OEMs' orders (i.e., to 
be conservative, since exact information on overseas orders is not 
available). In total, 3,338 in-service part 121 airplanes have already 
been equipped with TAWS or have already placed orders with the 
manufacturer (based on data in mid-1999; several hundred more airplanes 
probably will have been equipped by the date of publication of the 
rule). Of the 3,338 airplanes counted as voluntarily complying, 3,173 
are turbojets and 165 are large turboprops. Voluntary purchases of TAWS 
equipment before the implementation of the rule are not assumed to be 
an expense incurred due to regulation, but rather an independent 
industry decision to enhance operational safety. Thus, both the 
expected benefits and costs of this rule are reduced by the proportion 
of airplanes equipped with TAWS (or on order with TAWS included).
    For future airplanes, voluntary compliance has a substantial impact 
on the affected fleet. Excluding ATA member fleets, the remaining jets 
are 20 percent of the total part 121 jet fleet. The future new delivery 
jet forecast averages 280 per year. The estimated affected future jet 
fleet is then 20 percent of the anticipated deliveries. Voluntary 
compliance is much lower for part 121 turboprops than for jets. The 
proportion of total turboprop equipment not in compliance is nearly 70 
percent. Nevertheless, 30 percent compliance results in a significant 
reduction in the incremental costs of future deliveries (i.e., from the 
standpoint of a ``regulatory-required'' cost-impact). Future turboprop 
deliveries are estimated to average 100 per year with the annual 
affected amount equaling 69 or 70 airplanes. (This is a conservative 
assumption, since operators of much more than 30 percent of part 121 
turboprops would probably elect to equip their new airplanes with the 
most current GPWS/TAWS equipment)
    The part 121 affected fleet equals the remaining in-service part 
121 airplanes (i.e., after subtracting-out airplanes retired and 
airplanes under voluntary compliance) combined with newly manufactured 
airplanes estimated to be sold to operators who would not have 
voluntarily complied with this rule. The affected in-service part 121 
fleet equals 2,709 airplanes (or, 6,907 existing fleet, minus 860 
retirements, and minus 3,338 airplanes under voluntary compliance). The 
number of affected jets equals 1,644, large turboprops 710, and small 
turboprops 355. Over the 2001 through 2010 period, future new 
deliveries are 560 jet transports and 690 turboprop transports for a 
total of 1,250 airplanes. The total affected part 121 fleet thus equals 
approximately 4,000 airplanes.
    There has been a reduction in the CFIT accident rate since 1974, 
when the FAA first required GPWS in part 121 and certain part 135 
airplanes. However, some risks remain--in part due to differences in 
the capabilities of various generations of GPWS technologies. Risk 
reduction estimates for 14 CFR part 121 operations are based on the 
Volpe part 121/135 study and analyses of accident data by FAA and 
industry experts. These appraisals are true measures of risk reduction 
in that they fully consider the effect of TAWS on accident outcomes, 
rather than simply assume that all accidents will be prevented. The 
analysis is complicated by the fact that two vintages of GPWS 
technology were employed during the period being studied. Although the 
NPRM considered the TAWS impact in comparison to both early and current 
generation systems, this final rule analysis assumes that all the 
airplanes currently equipped with the basic system are in fact ``one 
level higher'' (i.e., have the current GPWS), a significantly more 
conservative assumption resulting in lower benefits. Risk reduction 
estimates were calculated by dividing the number of preventable 
accidents for a particular airplane/GPWS combination by the 
corresponding number of flight hours.
    From an evaluation of part 121 accidents during the 10-year period, 
1986-1995, the Volpe part 121/135 study concludes that TAWS would have 
prevented 6 CFIT accidents involving turbojet airplanes and 2 CFIT 
accidents involving turboprops.
    With respect to turbojets, only one accident involved an airplane 
equipped with current-generation GPWS. However, the Volpe part 121/135 
study concludes that in three other cases (involving airplanes equipped 
with early-generation systems), current-generation GPWS would not have 
prevented the accident. TAWS would

[[Page 16750]]

have prevented all four accidents. Therefore, the FAA estimates the 
risk reduction potential of TAWS relative to current-generation GPWS is 
approximately 0.038 accidents per million flight hours (4  
104.7 million flight hrs.). With respect to the turboprops, both 
accidents would have been prevented by TAWS, but not by GPWS; the 
comparable risk reduction rate is 0.118 accidents per million flight 
hours (2  16.972 million flight hrs.).
    After estimating the expected benefits for the fleet, total 
estimated present value benefits depends on the expected life after 
installation. The total present value benefits of this rule for part 
121 airplanes equal nearly $494 million.
    The FAA accepts the costs provided by the ATA for jets and by the 
RAA for turboprops. The combination of retirements and voluntary 
compliance substantially changes the affected fleet, especially for the 
impact on ATA member fleets operating in part 121. The FAA includes as 
part 121 operations all RAA turbine-powered airplanes classified as 
large cargo and passenger airplanes with more than 30 seats, plus 
nearly all of the RAA classified part 121/135 passenger airplanes with 
10 to 29 seats. Retirements reduce the proportion of older airplanes in 
the fleet; these airplanes have the highest average retrofit cost.
    After retirements and voluntary compliance, the expected jet fleet 
to be retrofitted equals 1,644 airplanes. Over the time period 2001 to 
2004, the present value expense of retrofitting this fleet equals 
$108,580,000. Similarly, the present value expense of retrofitting 355 
10 to 29 seat airplanes is estimated to be $9,660,000. Finally, the 
present value expense to retrofit 30+ seat airplanes (includes large 
cargo) is estimated to be $25,390,000. Over the period of 2001 to 2004 
total present value cost of retrofitting the affected fleet is equal to 
nearly $144 million.
    In addition to retrofitting the existing fleet, new airplanes will 
also incur the cost of installing TAWS. The FAA received a wide range 
of estimates for the cost of installing TAWS on new airplanes. Whereas 
the ATA cost estimate for new production airplanes is nearly $25,000, 
this rule imposes only the additional cost above the current GPWS 
equipment. The FAA estimate of $13,000 incremental cost for jets equals 
an incremental price increase of $10,000 for the TAWS, plus $1,000 
installation kit, plus additional labor of $2,000. Future turboprops 
would have had GPWS, so the incremental cost is the relevant estimate. 
The $3,800 turboprop incremental cost equals the incremental price 
increase of $2,000, plus $800 installation kit, plus additional labor 
of $1,000. There are no incremental costs incurred for training, 
maintenance, and fuel with TAWS versus GPWS.
    Over a ten year horizon for new deliveries, the present value of 
incremental expense for jets is nearly $5 million and for turboprops 
nearly $2 million. If the horizon is extended an additional ten years, 
the present value for new deliveries increases by approximately $3.4 
million. The total present value cost equals $144 million for 
retrofitted airplanes plus $7 million for new airplanes, or $151 
million.
    With estimated present value benefits of $494 million and present 
value costs of $151 million, the rule is clearly cost-beneficial for 
airplanes operated under part 121.

Part 135

    Similar to the case with part 121, incremental benefits and costs 
depend on several fleet-related factors, i.e., the existing fleet (and 
associated hours flown), expected retirements, voluntary compliance, 
and non-compliant airplane deliveries. For the purposes of this 
rulemaking, the cost/benefit analysis separates airplanes with 10 or 
more seats from those with 6 to 9 seats.
    The part 135 fleet today is composed of 2,455 airplanes with 6 to 9 
seats, and 334 airplanes with 10 or more seats. These airplanes are 
assumed to have a 4 percent retirement rate.
    There have been 421 TAWS units delivered to domestic United States 
operators and original equipment manufacturers (OEMs) for 6 to 9 seat 
airplanes. Operators have purchased 118 units and have ordered an 
additional 5 units. Fifty percent of OEM deliveries (152 of 303 total 
units) are assumed to be delivered to the existing 6 to 9 seat part 135 
fleet. Thus from a fleet of 2,455 airplanes, 275 are estimated to have 
voluntarily complied. For the part 135 airplanes with 10 or more seats 
(total fleet equals 334 airplanes), 25 TAWS units have been purchased 
by operators and an estimated 111 units by OEMs.
    After subtracting airplanes that are estimated to be retired or in 
voluntary compliance, the affected in-service fleet is estimated to be 
1,833 airplanes with 6 to 9 seats, and 171 airplanes with ten or more 
seats.
    Future annual airplane deliveries are assumed to equal five percent 
of the affected in-service fleet. The affected fleet equals 3,616 
airplanes through the year 2011.
    One of the main criticisms of the part 135 cost/benefit analysis in 
the NPRM was that the FAA used parts 91 and 121 accident rates for 6 to 
9 and 10 or more seat part 135 airplanes, respectively. The main reason 
for this was that most of the larger part 135 airplanes (those in 
scheduled service) involved in the CFIT accidents during the 1985 
through 1996 analysis period were ``moved into'' part 121 as a result 
of the 1995 commuter rule; thus the FAA excluded most of these earlier 
``part 135 accidents'' from the part 135 analysis. In addition, time 
constraints negated analysis of CFIT accidents involving both the 
larger and smaller part 135 airplanes. Since publication of the NPRM, 
the Volpe Center re-evaluated the accident data (docket contains 
accident analyses) involving part 135 airplanes, again with the 
emphasis of assessing the effectiveness of TAWS compared to current 
generation GPWS; the results of this analysis are incorporated in the 
benefits discussion that follows.
    Previous data on hours flown is ``distorted'' as a result of the 
part 121/135 ``shifts'' described above. In addition, FAA fleet data 
show that there has been a significant decline in the number of 10 or 
more seat turboprops and turbojets; there are only 111 turbojets and 
223 turboprops currently operating with 10 or more seats in part 135. 
Thus, historical data on hours flown had to be adjusted to reflect the 
definitional/regulatory change in the part 135 category. The current 
level of activity is the basis for evaluating future accident 
probabilities. The relatively few relevant part 135 accidents (i.e., 
due to the re-classification described above) and concomitantly fewer 
postulated future accidents logically reflect the reduced level of 
activity.
    As a proxy for hours flown by 6 to 9 and 10 or more seat part 135 
airplanes (the data was and still is not available by these specific 
size categories), the FAA used recently revised data on air taxi 
operations from its 1997 General Aviation and Air Taxi Survey. The 
earliest year for which revised annual hours are available is 1991. 
Since 1991 is approximately the mid-point of the 1985-96 accident 
evaluation period, hours flown for 1991 was applied to the current 
number of part 135 airplanes in the two size categories to approximate 
total annual hours for the fleet during the particular year(s) of the 
accident(s).
    Only one avoidable CFIT accident occurred involving a passenger-
carrying turboprop with 10 or more seats (all are non-scheduled). That 
accident occurred in Beluga, Alaska on December 22, 1989, and involved 
a Piper PA-31 airplane with 10 passenger seats; only the pilot, who was 
killed, was on board--the airplane was destroyed. Only TAWS would have 
prevented this accident. Another accident involved a

[[Page 16751]]

cargo airplane; that accident occurred in Destin, Florida on May 16, 
1991 and involved a Cessna CE-208B airplane with 2 cockpit seats; only 
one pilot, who was killed, was on board and the airplane was destroyed. 
Only TAWS would have prevented this accident. Even though most part 135 
cargo airplanes are not covered by the TAWS rule, the FAA believes it 
is appropriate to include this accident in the analysis, since the same 
model airplane could just as well have been carrying passengers 
(circumstances involving a CFIT accident would not differ between a 
cargo-carrying vs. a passenger-carrying airplane).
    Only one avoidable CFIT accident occurred involving part 135, 10 or 
more seat turbojets; the airplane involved was configured for cargo 
only. The accident occurred in Monroe, Louisiana on January 8, 1988, 
and involved a Learjet LJ-36A airplane with two cockpit crewmembers on 
board, both of whom were killed--the airplane was destroyed. Only TAWS 
would have prevented this accident. The FAA believes it is appropriate 
to include this accident in the analysis, since the same model airplane 
could just as well have been carrying passengers (see discussion above 
re turboprops also).
    One avoidable CFIT accident occurred involving a passenger-carrying 
turboprop with 6 to 9 passenger seats (covered by the rule whether 
scheduled or non-scheduled). The accident occurred in Casper, Wyoming 
on December 22, 1989, and involved a Mitsubishi MU-2B-35 airplane with 
6 passenger seats; 4 persons were on board and all were killed--the 
airplane was destroyed. TAWS (and current GPWS) would have prevented 
this accident.
    Two avoidable CFIT accidents occurred involving passenger-carrying 
turbojets with 6 to 9 passenger seats (covered by the rule whether 
scheduled or non-scheduled). One accident occurred in Gulkana, Alaska 
on August 20, 1985, and involved a Learjet LJ-24D airplane with 8 
passenger seats; 3 persons were on board and all were killed--the 
airplane was destroyed. TAWS (and current GPWS) would have prevented 
this accident. The second occurred in Juneau, Alaska on October 22, 
1985, and also involved a Learjet LJ-24D airplane, this one with 6 
passenger seats; 4 persons were on board and all were killed--the 
airplane was destroyed. TAWS (and current GPWS) would have prevented 
these accidents.
    As noted earlier, lifecycle benefits per airplane equal the 
annualized benefit for that airplane (which is a function of seating 
capacity, load factor, annual flight hours, etc.) discounted over the 
number of remaining years of service life. Fleet benefits, in turn, are 
computed by summing per-airplane lifecycle benefits over all affected 
airplanes.
    The results show benefits of $40.6 million for 6 to 9 seat 
airplanes and benefits of $47.9 million for 10 or more seat airplanes 
for total part 135 benefits of $88.5 million.
    The cost of TAWS equipment for part 135 airplanes depends on the 
class of TAWS equipment required for the specific group of part 135 
airplanes: Class B for airplanes with 6 to 9 seats and Class A for 
airplanes with ten or more seats. The Class B unit does not require an 
air data computer, radio altimeter, or a color display; these 
components (required in the units now identified as Class A) were 
largely responsible for the high compliance costs in the NPRM for 
airplanes with 6 to 9 seats. For newly produced 6 to 9 seat airplanes, 
the cost of TAWS equals the $7,000 unit price for TAWS plus $500 for 
installation. For existing 6 to 9 seat airplanes, the total retrofit 
cost is $12,500; this cost is comprised of a $7,000 price plus a dealer 
markup of $2,100, installation cost of $1,400, and an estimated STC 
cost of $2,000. The FAA estimates that the rule's incremental unit cost 
per 10 or more seat airplanes will equal the 10-29 seat part 121 
turboprop unit cost of $34,400. For newly delivered airplanes with 10 
or more seats, the incremental cost for TAWS is the additional cost 
above the GPWS that these airplanes would otherwise have been equipped 
with; this incremental unit cost equals $3,800, comprised of a price 
difference of $2,000, installation kit of $800, and installation labor 
of $1,000.
    The total TAWS cost for part 135 operators equals the incremental 
unit cost multiplied by the affected fleet. The present value cost of 
approximately $18 million for the in-service 6 to 9 seat passenger 
airplanes, equals the affected fleet distributed equally over the four 
years multiplied by a unit cost of $12,500. Similarly, the present 
value cost of approximately $4.7 million for the in-service 10 or more 
passenger airplanes equals the affected fleet distributed equally over 
the four years multiplied by a unit cost of $34,400. Over the period 
2000 to 2011, the incremental cost of 6 to 9 seat newly delivered 
airplanes equals approximately $7 million. Over the same period, the 
incremental cost for 10 or more seat newly delivered airplanes equals 
approximately $0.4 million. The total present value cost for part 135 
airplanes is $30,121,000.
    With present value benefits of approximately $88 million and 
present value costs of $30 million, the rule is clearly cost-beneficial 
for part 135 airplanes.

Part 91

    The fleet referred to as the affected 14 CFR part 91 airplanes, for 
the purposes of this analysis, is an estimate of the total affected 
fleet of U.S.-registered turbine-powered airplanes that are not 
affected by 14 CFR parts 121 and 135. This fleet is estimated to be 
comprised of approximately 6,000 turbojets and 6,000 turboprops and 
includes general aviation airplanes operating under part 91 (corporate, 
business, personal, instruction, aerial application, and other), large 
airplanes (having a seating capacity of 20 or more or a maximum payload 
capacity of 6,000 pounds or more) operating under 14 CFR part 125, and 
U.S.-registered airplanes operating under 14 CFR part 129. Whereas the 
analysis of airplanes affected by parts 121 and 135 made use of 
specific airplane-category data, the analysis of the affected part 91 
fleet uses aggregate-level estimates owing to the difficulty of 
gathering airplane or model specific data on airplanes operating under 
part 91.
    Based on recent contacts with industry and government sources, the 
FAA projects that approximately 240 turboprops and 350 turbojets will 
be delivered each year to operators falling under the 14 CFR part 91 
group. Benefit and cost estimates for newly manufactured airplanes are 
based on 10 years of deliveries. The conclusions of this report, with 
respect to the benefit/cost ratio for equipping newly manufactured 
airplanes, are not sensitive to these forecasts.
    Some voluntary efforts to install TAWS systems in part 91 airplanes 
are already occurring. According to FAA certification officials and 
industry sources, STCs for TAWS have been approved for the Beech C90, 
the Canadair CL-601, the Falcon 900B, and the Gulfstream GV. Gulfstream 
and Bombardier will include TAWS as standard equipment on new 
Gulfstream V and Global Express long-range business jets. Orders for 
TAWS equipment for new part 91 airplanes total slightly more than 160 
units, or approximately 30 percent of one year of deliveries.
    Estimates of the benefits of the rule are based on a Volpe part 91 
study of 44 accidents that met all of the following CFIT accident 
criteria: (1) Accident date between January 1, 1985 and December 31, 
1994; (2) turbine-powered airplane having 6 or more

[[Page 16752]]

passenger seats operating under 14 CFR part 91 flight rules; (3) 
airplane in controlled flight at the time of accident; (4) all airplane 
systems operating normally at time of accident; and (5) pilot(s) not 
impaired.
    Of the 44 accidents, 11 involved turbojets and 33 involved 
turboprops. Probable cause, as determined by the NTSB, was pilot error 
in all cases--principally through failure to maintain proper altitude, 
use of improper instrument flight rules or visual flight rules 
procedures, or poor planning/decision-making. Contributing factors 
included weather conditions and darkness in many cases. In two 
accidents, the NTSB assigned partial responsibility to FAA air traffic 
control problems. The 44 accidents resulted in 131 fatalities, 19 
seriously injured passengers, and destruction of 37 airplanes and 
substantial damage to 7 airplanes.
    The Volpe part 91 study determined that current-technology ground 
proximity warning systems could have prevented 33 of the 44 accidents 
(the 33 GPWS-preventable accidents accounted for 96 fatalities, 17 
serious injuries, 18 minor injuries, 27 destroyed airplanes, and 6 
substantially-damaged airplanes). Of the 11 accidents that were not 
likely to have been prevented by current-technology GPWS, the study 
found that 9 accidents could have been prevented by TAWS. In total, 
therefore, TAWS could have prevented 42 of the 44 accidents (all 33 of 
the accidents preventable by GPWS and the additional 9). The 42 TAWS-
preventable accidents accounted for 126 fatalities, 19 serious 
injuries, 26 minor injuries, 35 destroyed airplanes, and 7 
substantially damaged airplanes. Total part 91 present value benefits 
are $720.2 million. Adjusting (i.e., reducing) these estimated benefits 
by the 10 percent of the part 91 fleet voluntarily complying, results 
in benefits of approximately $648 million.
    While there are some nonrecurring costs, most of the total system 
costs include the equipment with installation, and the operating and 
maintenance costs. The equipment cost is $7,000 for in-service or newly 
manufactured airplanes. The Class B TAWS unit (requiring significantly 
less interface with existing/or needed upgraded avionics) dramatically 
reduces the expense to part 91 operators from that reported in the 
NPRM. Installation cost is $3,500 for in-service airplanes and $500 for 
newly manufactured airplanes. The part 91 total present value cost is 
$164.2 million.
    With estimated present value benefits of $648 million and present 
value costs of $164 million, the rule is clearly cost-beneficial for 
part 91 airplanes.

Conclusions

    On the basis of the preceding analyses, the FAA concludes that, for 
each of the groups of affected airplanes operating under parts 121, 
135, and 91, the benefits of TAWS exceed their costs. Total present 
value benefits of the rule are $1.23 billion, approximately 3.6 times 
the cost of $345 million. The benefit/cost ratios for the groups that 
are composed primarily of smaller airplanes (parts 91 and 135, which 
have a large number of 6 to 9 seat airplanes) are high in large part 
because of the development of the less costly Class B TAWS equipment 
that will be in effect under this final rule.

Final Regulatory Flexibility Determination and Analysis

    The Regulatory Flexibility Act of 1980 establishes ``as a principle 
of regulatory issuance that agencies shall endeavor, consistent with 
the objective of the rule and of applicable statutes, to fit regulatory 
and informational requirements to the scale of the business, 
organizations, and governmental jurisdictions subject to regulation.'' 
To achieve that principle, the Act requires agencies to solicit and 
consider flexible regulatory proposals and to explain the rationale for 
their actions. The Act covers a wide range of small entities, including 
small businesses, not-for-profit organizations, and small governmental 
jurisdictions.
    Agencies must perform a review to determine whether a proposed or 
final rule will have a ``significant economic impact on a substantial 
number of small entities.'' If the determination is that it will, the 
agency must prepare a regulatory flexibility analysis as described in 
the Act.
    Recently, the Office of the Small Business Administration (SBA) 
published new guidance for the use of Federal agencies in responding to 
the requirements of the Regulatory Flexibility Act, as amended. 
Application of that guidance to this rule indicates that it will have a 
significant impact on a substantial number of small entities. 
Accordingly, a full regulatory flexibility analysis was conducted.

1. A description of the reasons why action by the agency is being 
considered

    The agency is considering this action in response to a history of 
controlled flight into terrain accidents, NTSB recommendations, and 
subsequent analysis performed at the request of the agency. This rule 
is an implementation of the agency's mission to improve aviation 
safety.

2. A succinct statement of the objectives of, and legal basis, for the 
rule

    The objective of this rule is to improve aviation safety by 
requiring the installation or retrofit of terrain awareness and warning 
systems on turbine-powered airplanes with six or more passenger seats.
    The legal basis for the rule derives from Title 49 U.S.C. 44701 
which authorizes the FAA Administrator to promote the safety of flight 
of civil aircraft in air commerce by prescribing, in part, minimum 
standards governing the design and construction of aircraft, aircraft 
engines, and propellers, as may be required in the interest of safety.

3. A description of the projected reporting, recordkeeping, and other 
compliance requirements of the proposed rule

    Recordkeeping will be minimal. Recordkeeping and other compliance 
requirements will be similar to those for radio-navigation equipment 
that is currently in use.

4. An identification, to the extent practicable, of all relevant 
federal rules that may duplicate, overlap, or conflict with the final 
rule

    The FAA is unaware of any federal rules that would duplicate, 
overlap, or conflict with the final rule.

5. A description and estimate of the number of small entities to which 
the rule will apply

    Entities (both large and small) potentially affected by the rule 
include manufacturers of transport category airplanes (North American 
Industry Classification System (NAICS) code 336411 ``Aircraft 
Manufacturing''), manufacturers of ground proximity warning equipment 
(NAICS 334511 ``Search, Detection, Navigation, Guidance, Aeronautical, 
and Nautical Systems and Instruments Manufacturing''), scheduled air 
carriers (NAICS 48111 and 481112 ``Scheduled Passenger Air 
Transportation'' and ``Scheduled Freight Air Transportation''), and 
nonscheduled air carriers (NAICS 481212, 481211, and 48799, 
``Nonscheduled Chartered Freight Air Transportation,'' ``Nonscheduled 
Chartered Passenger Air Transportation,'' and ``Scenic and Sightseeing 
Transportation, Other'').
    More specifically, the rule will affect many small entities that 
operate turbine-powered airplanes seating six or more passengers under 
14 CFR part 91 (e.g., small businesses, governments, and

[[Page 16753]]

individuals). There are thousands of operators of such airplanes, and, 
therefore, potentially thousands of entities representing hundreds of 
industries, organizations, and institutions. Costs per entity will be 
dependent on the number of airplanes affected and the (comparatively 
modest) cost of purchasing and installing Class B TAWS equipment.
    An additional group of small entities who operate under 14 CFR part 
135 that is likely to be affected by this regulation consists of 
operators of charter/on-demand air travel services, small operators of 
scheduled air service, and fixed-base operators (who often provide 
unscheduled air taxi service). Charter/on-demand operators typically 
have relatively few employees and low annual revenues. For this 
analysis the FAA classifies entities with 1,500 or fewer employees as a 
``small entity.'' There are believed to be only about 60 out of the 
approximately 2,800 part 135 operators that have more than 1,500 
employees, so that more than 2,700 part 135 operators will be 
classified as ``small entities.'' Half of these entities have less than 
8 or 10 employees. The actual financial impact of the rule on any one 
of these entities will depend on the number of affected airplanes 
operated and whether Class A or B TAWS equipment will be required on 
these airplanes.
    There are estimated to be more than 100 part 121 air carriers 
engaged in carrying passengers. Out of this total, over half are 
estimated to be small entities, based on having 1,500 or fewer 
employees. The actual financial impact on these entities will depend on 
the number of affected airplanes and the cost of purchasing and 
installing Class A TAWS equipment. As noted in previous discussions, a 
significant portion of the part 121 fleet operators, primarily the 
members of the Air Transport Association, is expected to voluntarily 
install the equipment required by this rule. The entities voluntarily 
complying with the rule are assumed to bear no costs as a direct result 
of this rule.

6. Affordability Analysis

    In response to public comments and small business concerns, the 
initial proposed rule has been modified to reduce the compliance costs 
for operators with airplanes operating only under part 91, and under 
part 135 with 6 and 9 passenger seats. Most of these operators are 
expected to be small entities and will benefit from a higher level of 
safety with the lower cost Class B TAWS equipment. In the initial NPRM 
regulatory evaluation, the expected compliance cost to part 91 
operators was estimated to be between $27,000 and $30,000 per airplane. 
In the final rule, Class B TAWS compliance cost is estimated to be 
slightly more than $10,000 per airplane. As an estimate of 
affordability, for general aviation turboprops with from one to nine 
seats and one or two engines, average airplane values are estimated to 
be $679,000 and $572,000, respectively. Thus the Class B TAWS equipment 
for these airplanes will cost between 1.5 percent and 2.0 percent of 
these airplanes' values. While it is very difficult to specify how 
affordable this rule will be for a small entity, the requirement of 
Class B TAWS (rather than Class A TAWS) substantially reduces the 
compliance cost for many small entities. Small entities which will be 
required to install Class A TAWS equipment will incur significantly 
higher costs than those required to install Class B TAWS equipment. 
Lastly, those operators engaged in chemical/agricultural applications, 
parachuting, and firefighting are excluded from the requirements of 
this rule. Most of these entities have fewer than 1,500 employees and 
thus are classified as small entities under this analysis.

7. Competitiveness Analysis

    In the aviation industry, particular commercial market segments 
tend to be served by airplanes with similar seat size that operate 
under the same part of the CFR. For those markets served only by 
operators who will install equipment having roughly equal cost, much of 
the full cost of this rule could be passed on to their customers. In 
this case, there will be no significant change in the competitiveness 
among operators. For a market where competitors operate similar size 
airplanes but with different avionics, the cost incurred as a result of 
this rule may differ significantly among operators. Operators of 
airplanes with older avionics who will be required to install Class A 
TAWS equipment are expected to incur higher costs than those operating 
airplanes with newer equipment. Depending upon the mix of equipment 
serving a market, operators with older avionics equipment may be less 
able to pass on most of the cost of this rule.

8. Disproportionality Analysis

    It is not clear that this rule imposes systematically higher or 
lower proportionate cost increases on smaller, as opposed to larger 
entities. The compliance cost of the rule depends upon the affected 
airplanes and how they are operated. The net impact on profitability to 
an operator may be affected by the costs imposed on competitors by the 
rule. The cost to an operator rises as the number of airplanes 
increases. In terms of the number of airplanes, the rule imposes 
proportional costs on operators under part 91 and those operating 
airplanes with 6 to 9 seats under part 135. It is expected that these 
operators are primarily small entities. The retrofit of Class A TAWS 
equipment will cost more to operators of airplanes with older avionics 
equipment. The age of the avionics within an airplane is not 
necessarily related to the size of the entity that operates the 
airplane. Thus, the FAA can not specify whether this rule will have a 
disproportionate impact on small entities.

9. Description of Alternatives

    The agency has considered a number of alternatives to the rule. The 
FAA finds that the rule chosen will achieve a level of safety that is 
equivalent to or greater than that of the alternatives considered, and 
do this at a lower cost to the affected entities.
    The alternatives that have been considered can be grouped into 
three categories:

     Exclude small entities
     Extend compliance deadline for small entities
     Establish lesser technical requirements for small entities

    The FAA concludes that the option to exempt small entities from all 
the requirements of the rule is not justified. In fact, as noted in the 
preamble and in Section II of this document, the accident history of 
part 91 operators (many of whom are small entities) forms the basis of 
the NTSB's recommendation to require ground proximity warning systems 
on smaller turbojet and turboprop airplanes. However, the final rule 
does permit the use of TAWS equipment that meets the requirements for 
Class B equipment in TSO-C151 in airplanes operating under part 91 and 
for airplanes having 6 to 9 passenger seats operating under part 135. 
This requirement is somewhat less stringent as well as being less 
costly than the Class A equipment required for part 121 operations and 
larger airplanes operating under part 135; both pieces of equipment 
provide the same level of safety for the TAWS functions.
    The FAA also considered options that will lengthen the compliance 
period for small operators. The FAA believes that the equipment chosen 
requirement will place a modest burden on small entities that arises 
from making expenditures on equipment at an earlier date. Small 
entities will have four years from the effective date of the rule to 
complete

[[Page 16754]]

retrofit work. Delaying the compliance deadline beyond the current 
proposal would not have resulted in significantly lower downtime or 
certification costs. Rather, the additional cost incurred will equal 
the modest return on capital (that will be spent on TAWS equipment) 
that would have been realized during the short time that the operator 
might have postponed the retrofit. Lengthening the compliance period 
would have exposed airplane occupants to significant safety risks for a 
longer period of time.
    Finally, the FAA is not in favor of compliance options that will 
permit non-TAWS technologies. For airplanes not equipped with any 
ground proximity warning system, TAWS units will provide up to 23% 
greater CFIT risk reduction over current-generation GPWS at very little 
additional cost. For operators of part 91 airplanes, the use of a TAWS 
that is made possible with the use of data provided by GPS and an 
encoding altimeter, as is now permitted under the revised rule, will 
provide the benefits of a TAWS at significantly lower cost than with 
alternative technologies. It is noted that, in the NPRM, the present 
value of total costs for the part 91 fleet was estimated to be $415 
million. Under the final rule, these costs are estimated to be $164 
million, less than 40 percent of the level that would have been imposed 
under the initially proposed rule. It is estimated that several 
thousand part 91 operators will be affected by this rule. Similarly, 
approximately 2,800 part 135 (air taxi and similar) operators will be 
affected, as will approximately 100 part 121 (air carrier) operators. 
The precise impact on a particular operator will depend on the number 
of turbine-powered airplanes operated and will be larger for operators 
with greater numbers of airplanes.
    The FAA has determined that this rule will impact small entities, 
has analyzed the impact of this rule on small entities, and has made 
efforts to reduce the impact. There are literally thousands of firms 
with less than 1,500 employees that will be affected by this rule. More 
than 1,000 of these firms are expected to have fewer than 10 employees. 
In response to public comments and with the availability of new 
technology, the FAA will require a substantially less expensive and 
easier to install TAWS for part 91 and some part 135 operators. It is 
expected most of the reduced compliance cost will benefit small 
entities.

International Trade Impact Assessment

    Recognizing that domestic regulations often affect international 
trade, the Office of Management and Budget directs Federal Agencies to 
assess whether or not a rule or regulation will affect any trade-
sensitive activity. It is recognized that the rule could potentially 
affect international trade by burdening domestic businesses or air 
carriers with requirements that are not applicable to their foreign 
competitors. In general, the FAA believes potential international trade 
impacts associated with the rule will be negligible. Many domestic and 
foreign air carriers are already voluntarily installing TAWS equipment 
in recognition of the substantial safety benefits. A summary of 
potential impacts follows.

Potential impact to domestic airplane manufacturers.

    The FAA believes that the rule will have a negligible effect on the 
competitive position of domestic airframe manufacturers. Under the 
rule, domestic manufacturers could continue to offer basic GPWS units 
on airplanes sold to foreign customers (if the airplane is not U.S.-
registered). Foreign airframe manufacturers, on the other hand, will be 
required to equip airplanes sold to U.S. customers (operating under 14 
CFR parts 91, 121, or 135) with TAWS.

Potential impact to domestic airplane leasing firms.

    Domestic firms leasing aircraft to foreign operators may be 
adversely affected by the part 91 provisions of the rule. Domestic 
leasing companies, for liability reasons or to position themselves to 
lease to both 14 CFR part 121 and foreign carriers, often choose to 
maintain U.S.-registered fleets. Thus, their lease prices may reflect 
TAWS retrofit costs while the prices of foreign competitors may not. 
(In some cases, the lessee is directly responsible for modifications 
required by airworthiness directive or regulations--but in either case 
the disincentive effect is the same).
    Given the small cost of TAWS relative to average airplane values, 
however, the FAA believes the potential international trade impact to 
be small. Also, TAWS equipped airplanes will be safer and thus more 
attractive to potential lessees--and their passengers. Increased 
patronage attributable to the operation of safer airplanes will also 
partially offset the costs of compliance.

Potential impact to domestic air carriers.

    The potential impact to air carriers is, again, a function of the 
aircraft registration. Foreign air carriers operating U.S.-registered 
airplanes will be required to install TAWS as will U.S. air carriers. 
To this extent, operators of U.S. registered airplanes will have costs 
that may not be required of non-U.S. registered competitors. Again, 
however, TAWS equipment costs will be a very small fraction of in-
service airplane values, provide a known safety feature, and represent 
a negligible portion of new airplane values. Also, CFIT accidents are a 
leading cause of commercial aviation fatalities worldwide. It is likely 
that knowledgeable passengers would pay the small difference in price 
to travel on an airplane equipped with TAWS. Voluntary industry 
initiatives to install enhanced ground proximity warning systems are 
consistent with the view that TAWS benefits far exceed its costs, and 
could have beneficial effects for domestic airlines competing for 
international passenger traffic.

Executive Order 13132, Federalism

    The FAA has analyzed this final rule under the principles and 
criteria of Executive Order 13132, Federalism. The FAA determined that 
this action will not have a substantial direct effect on the States, or 
the relationship between the national Government and the States, or on 
the distribution of power and responsibilities among the various levels 
of government. Therefore, the FAA has determined that this final rule 
does not have federalism implications.

Unfunded Mandates Reform Act

    Title II of the Unfunded Mandates Reform Act of 1995 (the Act), 
enacted as Pub. L. 104-4 on March 22, 1995 (the Act), codified in 2 
U.S.C. 1501-1571, requires each Federal agency, to the extent permitted 
by law, to prepare a written assessment of the effects of any Federal 
mandate in a proposed or final agency rule that may result in the 
expenditure by State, local, and tribal governments, in the aggregate, 
or by the private sector, of $100 million or more (adjusted annually 
for inflation) in any one year. Section 204(a) of the Act, 2 U.S.C. 
1534(a), requires the Federal agency to develop an effective process to 
permit timely input by elected officers (or their designees) of State, 
local, and tribal governments on a proposed ``significant 
intergovernmental mandate.'' A ``significant intergovernmental 
mandate'' under the Act is any provision in a Federal agency regulation 
that will impose an enforceable duty upon State, local, and tribal 
governments, in the aggregate, of $100 million (adjusted annually for 
inflation) in any one year. Section 203 of the Act, 2 U.S.C. 1533, 
which supplements section 204(a), provides that before establishing any 
regulatory requirements that might significantly or uniquely affect 
small governments, the agency shall have developed a plan that,

[[Page 16755]]

among other things, provides for notice to potentially affected small 
governments, if any, and for a meaningful and timely opportunity to 
provide input in the development of regulatory proposals or rules.
    This final rule does not contain a Federal intergovernmental or 
private sector mandate that exceeds $100 million in any one year.

Environmental Analysis

    FAA Order 1050.1D defines FAA actions that may be categorically 
excluded from preparation of a National Environmental Policy Act (NEPA) 
environmental assessment or environmental impact statement. In 
accordance with FAA Order 1050.1D, appendix 4, paragraph 4(j), this 
rulemaking action qualifies for a categorical exclusion.

Energy Impact

    The energy impact of the notice has been assessed in accordance 
with the Energy Policy and Conservation Act (EPCA) P.L. 94-163, as 
amended (43 U.S.C. 6362) and FAA Order 1053.1. It has been determined 
that the final rule is not a major regulatory action under the 
provisions of the EPCA.

List of Subjects

14 CFR Part 91 and 135

    Aircraft, Aviation safety.

14 CFR Part 121

    Aircraft, Aviation safety, Safety.

The Amendment

    In consideration of the foregoing, the Federal Aviation 
Administration amends parts 91, 121, and 135 of Title 14 Chapter 1, of 
the Code of Federal Regulations as follows:

PART 91--GENERAL OPERATING AND FLIGHT RULES

    1. The authority citation for part 91 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 1155, 40103, 40113, 40120, 44101, 
44111, 44701, 44709, 44711, 44712, 44715, 44716, 44717, 44722, 
46306, 46315, 46316, 46504, 46506-46507, 47122, 47508, 47528-47531, 
articles 12 and 29 of the Convention on International Civil Aviation 
(61 stat. 1180).

    2. Section 91.223 is added to read as follows:


Sec. 91.223  Terrain awareness and warning system.

    (a) Airplanes manufactured after March 29, 2002. Except as provided 
in paragraph (d) of this section, no person may operate a turbine-
powered U.S.-registered airplane configured with six or more passenger 
seats, excluding any pilot seat, unless that airplane is equipped with 
an approved terrain awareness and warning system that as a minimum 
meets the requirements for Class B equipment in Technical Standard 
Order (TSO)-C151.
    (b) Airplanes manufactured on or before March 29, 2002. Except as 
provided in paragraph (d) of this section, no person may operate a 
turbine-powered U.S.-registered airplane configured with six or more 
passenger seats, excluding any pilot seat, after March 29, 2005, unless 
that airplane is equipped with an approved terrain awareness and 
warning system that as a minimum meets the requirements for Class B 
equipment in Technical Standard Order (TSO)-C151.

(Approved by the Office of Management and Budget under control 
number 2120-0631)

    (c) Airplane Flight Manual. The Airplane Flight Manual shall 
contain appropriate procedures for--
    (1) The use of the terrain awareness and warning system; and
    (2) Proper flight crew reaction in response to the terrain 
awareness and warning system audio and visual warnings.
    (d) Exceptions. Paragraphs (a) and (b) of this section do not apply 
to--
    (1) Parachuting operations when conducted entirely within a 50 
nautical mile radius of the airport from which such local flight 
operations began.
    (2) Firefighting operations.
    (3) Flight operations when incident to the aerial application of 
chemicals and other substances.

PART 121--OPERATING REQUIREMENTS; DOMESTIC, FLAG, AND SUPPLEMENTAL 
OPERATIONS

    3. The authority citation for part 121 continues to read as 
follows:

    Authority: 49 U.S.C. 106(g), 40113, 40119, 44101, 44701-44702, 
44705, 44709-44711, 44713, 44716-44717, 44722, 44901, 44903-44904, 
44912, 46105.

    4. Section 121.354 is added to read as follows:


Sec. 121.354  Terrain awareness and warning system.

    (a) Airplanes manufactured after March 29, 2002. No person may 
operate a turbine-powered airplane unless that airplane is equipped 
with an approved terrain awareness and warning system that meets the 
requirements for Class A equipment in Technical Standard Order (TSO)-
C151. The airplane must also include an approved terrain situational 
awareness display.
    (b) Airplanes manufactured on or before March 29, 2002. No person 
may operate a turbine-powered airplane after March 29, 2005, unless 
that airplane is equipped with an approved terrain awareness and 
warning system that meets the requirements for Class A equipment in 
Technical Standard Order (TSO)-C151. The airplane must also include an 
approved terrain situational awareness display.

(Approved by the Office of Management and Budget under control 
number 2120-0631)

    (c) Airplane Flight Manual. The Airplane Flight Manual shall 
contain appropriate procedures for--
    (1) The use of the terrain awareness and warning system; and
    (2) Proper flight crew reaction in response to the terrain 
awareness and warning system audio and visual warnings.
    5. Section 121.360 is amended by adding paragraph (g) to read as 
follows:


Sec. 121.360  Ground proximity warning-glide slope deviation alerting 
system.

* * * * *
    (g) This section expires on March 29, 2005.

PART 135--OPERATING REQUIREMENTS: COMMUTER AND ON-DEMAND OPERATIONS

    6. The authority citation for part 135 continues to read as 
follows:

    Authority: 49 U.S.C. 106(g), 44113, 44701-44702, 44705, 44709, 
44711-44713, 44715-44717, 44722.

    7. Section 135.153 is amended by adding paragraph (f) to read as 
follows:


Sec. 135.153  Ground proximity warning system.

* * * * *
    (f) This section expires on March 29, 2005.
    8. Section 135.154 is added to read as follows:


Sec. 135.154  Terrain awareness and warning system.

    (a) Airplanes manufactured after March 29, 2002:
    (1) No person may operate a turbine-powered airplane configured 
with 10 or more passenger seats, excluding any pilot seat, unless that 
airplane is equipped with an approved terrain awareness and warning 
system that meets the requirements for Class A equipment in Technical 
Standard Order (TSO)-C151. The airplane must also include an approved 
terrain situational awareness display.
    (2) No person may operate a turbine-powered airplane configured 
with 6 to 9 passenger seats, excluding any pilot seat, unless that 
airplane is equipped with an approved terrain awareness and

[[Page 16756]]

warning system that meets as a minimum the requirements for Class B 
equipment in Technical Standard Order (TSO)-C151.
    (b) Airplanes manufactured on or before March 29, 2002:
    (1) No person may operate a turbine-powered airplane configured 
with 10 or more passenger seats, excluding any pilot seat, after March 
29, 2005, unless that airplane is equipped with an approved terrain 
awareness and warning system that meets the requirements for Class A 
equipment in Technical Standard Order (TSO)-C151. The airplane must 
also include an approved terrain situational awareness display.
    (2) No person may operate a turbine-powered airplane configured 
with 6 to 9 passenger seats, excluding any pilot seat, after March 29, 
2005, unless that airplane is equipped with an approved terrain 
awareness and warning system that meets as a minimum the requirements 
for Class B equipment in Technical Standard Order (TSO)-C151.

(Approved by the Office of Management and Budget under control 
number 2120-0631)

    (c) Airplane Flight Manual. The Airplane Flight Manual shall 
contain appropriate procedures for--
    (1) The use of the terrain awareness and warning system; and
    (2) Proper flight crew reaction in response to the terrain 
awareness and warning system audio and visual warnings.

    Issued in Washington, DC, on March 23, 2000.
Jane F. Garvey,
Administrator.
[FR Doc. 00-7595 Filed 3-27-00; 8:45 am]
BILLING CODE 4910-13-U