[Federal Register Volume 64, Number 102 (Thursday, May 27, 1999)]
[Proposed Rules]
[Pages 28770-28771]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-13233]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Parts 91, 121, and 135


Terrain Awareness and Warning System

AGENCY: Federal Aviation Administration (DOT).

ACTION: Notice of availability for public comment.

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SUMMARY: This document announces the availability of and requests 
comments on a revised proposed Technical Standard Order (TSO) C151, 
Terrain Awareness and Warning System (TAWS). The proposed TSO 
prescribes the minimum operational performance standards that TAWS must 
meet to be identified with the applicable TSO marking.

DATES: Comments submitted must be received on or before July 9, 1999.

ADDRESSES: Send all comments on the proposed technical standard order 
to: Federal Aviation Administration (FAA), Aircraft Certification 
Service, Aircraft Engineering Division, Avionic Systems Branch, AIR-
130, 800 Independence Avenue, SW., Washington, DC 20591. Or deliver 
comments to: Federal Aviation Administration, Room 815, 800 
Independence Avenue, SW., Washington, DC 20591.

FOR FURTHER INFORMATION CONTACT: Michelle Swearingen, Federal Aviation 
Administration (FAA), Aircraft Certification Service, Aircraft 
Engineering Division, Avionic Systems Branch, AIR-130, 800 Independence 
Avenue, SW., Washington, DC 20591, Telephone: (202) 267-3817, FAX: 267-
5340.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to comment on the proposed TSO 
listed in this document by submitting such written data, views, or 
arguments, as they desire, to the aforementioned specified address. 
Comments must be marked ``Comments to TSO C151.'' Comments received on 
the proposed technical standard order may be examined, both before and 
after the closing date, in Room 815, FAA Headquarters Building (FOB-
10A), 800 Independence Avenue, SW., Washington, DC 20591, weekdays 
except Federal holidays, between 8:30 a.m. and 4:30 p.m. All 
communications received on or before the closing date for comments 
specified will be considered by the Director of the Aircraft 
Certification Service before issuing the final TSO.

Background

    The FAA is developing a new technical standard order, TSO-C151, 
Terrain Awareness and Warning System. This TSO will prescribe the 
minimum operational performance standards that TAWS equipment must meet 
to be identified with the TSO-C151 Class A or Class B marking. This is 
the second opportunity for the public and the industry to review and 
comment upon the proposed TSO before the FAA publishes it as a final 
document. The FAA is giving this second opportunity for the following 
two reasons.
    First, the FAA has revised significantly the proposed TSO as a 
result of public comments. On November 4, 1998, the FAA published in 
the Federal Register (63 FR 59494, November 4, 1998) a notice of 
availability for public comment that announced the availability of and 
requested comments on proposed TSO-C151, Terrain Awareness and Warning 
System. In response to the TSO notice of availability, commenters 
submitted a large number of suggested changes, approximately 300, to 
the proposed TSO. In trying to be as flexible and as accommodating as 
technically feasible, the FAA accepted and included most of the 
suggested changes. As a result, the current proposed version is 
significantly different than what was originally proposed with the 
initial notice of availability.

[[Page 28771]]

    Second, the FAA has included two classes of TAWS equipment in the 
current version of the proposed TSO. On August 26, 1998, the FAA 
published in the Federal Register (63 FR 45628, August 26, 1998) a 
notice of proposed rulemaking (NPRM). That NPRM proposed to amend 14 
CFR part 91, General Operating and Flight Rules, by adding new rules 
that prohibit the operation of certain airplanes unless those airplanes 
are equipped with a TAWS that meets the requirements of the proposed 
TSO-C151. In response to the NPRM, the FAA received over 250 comments. 
Having reviewed the comments, the FAA is making changes to its proposed 
rule based on those comments. One significant change is to develop two 
classes of TAWS equipment, known as Class A and Class B. TSO-C151 Class 
A equipment will be required for all turbine powered airplanes operated 
under 14 CFR part 121 and for turbine powered airplanes configured for 
10 or more passenger seating operating under 14 CFR part 135. TSO-C151 
Class B equipment will be the minimum requirement for turbine powered 
airplanes configured with 6 or more passenger seats operating under 14 
CFR part 91 and for turbine powered airplanes configured with 6 to 9 
passenger seating operating under 14 CFR part 135. The proposed TSO-
C151 has been revised to include the airworthiness requirements for 
both Class A and Class B equipment. The original proposed TSO 
associated with the initial notice of availability did not include two 
classes of TAWS equipment.
    Both classes of equipment--Class A and Class B--include the TAWS 
features of comparing airplane position information to an on board 
terrain database then providing appropriate caution and warning alerts 
if necessary. The Class A equipment includes, in addition to the TAWS 
features, ground proximity warning system (GPWS) functions. There 
currently are International Civil Aviation Organizations (ICAO) and FAA 
(14 CFR parts 121 & 135) requirements for all part 121 and certain part 
135 airplanes to carry GPWS. Therefore Class A equipment includes both 
TAWS and GPWS features. The existing 14 CFR parts 121 and 135 rules for 
GPWS are being revised to make them compatible with the proposed new 14 
CFR part 91 TAWS rule. Class B equipment is the basic TAWS equipment 
and is required as minimum equipment by the new FAR Part 91 TAWS rule. 
Class A equipment, which includes both TAWS and GPWS, is required by 
the revised part 121 and part 135 rules for those airplanes that 
currently must carry GPWS. The FAA is requiring one level of safety for 
TAWS while still maintaining existing ICAO and FAA GPWS requirements 
for turbine-powered commercial airplanes. This TSO will be the means to 
obtain FAA approval of TAWS product(s).

How To Obtain Copies

    A copy of the revised proposed TSO-C151 may be obtained via 
Internet (http://www.faa.gov/avr/air/airhome.htm) or on requests from 
the individual listed under FOR FURTHER INFORMATION CONTACT.
    The revised proposed TSO references several RTCA, Inc. documents 
that contain specific requirements related to the TSO. RTCA Document 
No. DO-161A, ``Minimum Performance Standards--Airborne Ground Proximity 
Warning Equipment,'' dated May 27, 1976; DO-160D, ``Environmental 
Conditions and Test Procedures for Airborne Equipment,'' dated July 29, 
1997; DO-178B, ``Software Considerations in Airborne Systems and 
Equipment Certification,'' dated December 1, 1992; and DO-200A, 
``Preparation, Verification and Distribution of User-Selectable 
Navigation Data Bases,'' dated November 28, 1998, may be purchased from 
the RTCA Inc., 1140 Connecticut Avenue, NW., Suite 1020, Washington, DC 
22036. Copies of the RTCA documents may be inspected at the location 
specified under ADDRESSES. However, those documents are copyrighted and 
may not be copied without the written consent of RTCA, Inc.

    Issued in Washington, DC, on May 19, 1999.
James C. Jones,
Manager, Aircraft Engineering Division, Aircraft Certification Service.
[FR Doc. 99-13233 Filed 5-26-99; 8:45 am]
BILLING CODE 4910-13-M