[Federal Register Volume 66, Number 52 (Friday, March 16, 2001)]
[Proposed Rules]
[Pages 15203-15206]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-6531]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM185; Notice No. 25-01-02-SC]


Special Conditions: Enhanced Vision System (EVS) for Gulfstream 
Model G-V Airplane

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed special conditions.

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SUMMARY: This notice proposes special conditions for Gulfstream Model 
G-V airplanes. These airplanes, as modified by Gulfstream Aerospace 
Corporation, will have novel or unusual design features associated with 
a head-up display (HUD) system modified to display forward-looking 
infrared (FLIR) imagery. The regulations applicable to pilot 
compartment view do not contain adequate or appropriate safety 
standards for this design feature. These proposed special conditions 
contain the additional safety standards that the Administrator 
considers necessary to establish a level of safety equivalent to that 
provided by the existing airworthiness standards.

DATES: Comments must be received on or before April 30, 2001.

ADDRESSES: Comments on these special conditions may be mailed in 
duplicate to: Federal Aviation Administration, Transport Airplane 
Directorate, Attention: Rules Docket (ANM-114), Docket No. NM185, 1601 
Lind Avenue SW., Renton, Washington 98055-4056; or delivered in 
duplicate to the Transport Airplane Directorate at that address. All 
comments must be marked: Docket No. NM185. Comments may be inspected in 
the Rules Docket weekdays, except Federal holidays, between 7:30 a.m. 
and 4 p.m.

FOR FURTHER INFORMATION CONTACT: Dale Dunford, FAA, Transport Standards 
Staff, ANM-111, Transport Airplane Directorate, Aircraft Certification 
Service, 1601 Lind Avenue SW., Renton, Washington 98055-4056; telephone 
(425) 227-2239; fax (425) 227-1100; e-mail: [email protected].

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of 
these proposed special conditions by submitting such written data, 
views, or arguments, as they may desire. Communications should identify 
the

[[Page 15204]]

regulatory docket number (NM185) and be submitted in duplicate to the 
address specified above. All communications received on or before the 
closing date for comments will be considered by the Administrator. 
These proposed special conditions may be changed in light of the 
comments received. All comments received will be available in the Rules 
Docket for examination by interested persons, both before and after the 
closing date for comments. A report summarizing each substantive public 
contact with FAA personnel concerning this rulemaking will be filed in 
the docket. Commenters wishing the FAA to acknowledge receipt of their 
comments submitted in response to these proposed special conditions 
must include with those comments a self-addressed, stamped postcard on 
which the following statement is made: ``Comments to Docket No. 
NM185.'' The postcard will be date-stamped and returned to the 
commenter.

Background

    On February 13, 1998, Gulfstream Aerospace Corporation, 4150 Donald 
Douglas Drive, Long Beach, California 90808, applied for a supplemental 
type certificate (STC) to modify Gulfstream Model G-V airplanes. The 
Model G-V is a small transport category airplane. The Model G-V 
airplanes are powered by two BMW--Rolls Royce Mark BR700-710A1-10 
engines, and have a maximum takeoff weight of 90,500 pounds. This 
airplane operates with a two-pilot crew and can hold up to 19 
passengers.
    The modification incorporates the installation of an Enhanced 
Vision System (EVS). This system consists of a previously approved 
Honeywell 2020 head-up display (HUD) system that is modified to display 
forward-looking infrared (FLIR) imagery provided by a Kollsman FLIR 
assembly. The EVS is novel or unusual technology for which the FAA has 
no certification criteria. Title 14, Code of Federal Regulations (14 
CFR) Sec. 25.773 (``Pilot compartment view''), prohibits visual 
distortions, glare, and reflections that could interfere with the 
pilot's normal duties. That regulation was not written in anticipation 
of an imagery display that could interfere with the pilot's forward 
field of view. Because Sec. 25.773 does not provide for any 
alternatives or considerations for such a novel or unusual system as 
the EVS, the FAA finds it necessary to establish safety requirements 
that ensure an equivalent level of safety and effectiveness of the 
pilot compartment view as intended by the regulation.
    To maintain an equivalent level of safety with Sec. 25.773, the 
fundamental principle must be that the combination of what the pilot 
can see in the FLIR image, and what can be seen through and around the 
image display, must be as safe and effective as the view without the 
EVS image. Other applications for certification of such technology are 
anticipated in the near future and magnify the need to establish FAA 
safety standards that can be applied consistently for all such 
approvals.

Type Certification Basis

    Under the provisions of Sec. 21.101 (``Designation of applicable 
regulations''), Gulfstream Aerospace Corporation must show that the 
Gulfstream Model G-V airplanes, as changed, comply with the regulations 
in the U.S. type certification basis established for the Model G-V 
airplane. The U.S. type certificate basis established for the Model G-V 
airplane is established in accordance with Sec. 21.21 (``Issue of type 
certificate * * *'') and Sec. 21.17 (``Designation of applicable 
regulations''), and the type certification application date. The U.S. 
type certification basis for this model airplane is listed in Type 
Certificate Data Sheet No. A12EA.
    If the Administrator finds that the applicable airworthiness 
regulations (i.e., part 25, as amended) do not contain adequate or 
appropriate safety standards for the Gulfstream Model G-V airplanes 
modified by Gulfstream Aerospace Corporation because of a novel or 
unusual design feature, special conditions are prescribed under the 
provisions of Sec. 21.16 (``Special conditions'').
    In addition to the applicable airworthiness regulations and special 
conditions, these Gulfstream Model G-V airplanes must comply with the 
fuel vent and exhaust emission requirements of part 34 and the noise 
certification requirements of part 36.
    Special conditions, as appropriate, are issued in accordance with 
Sec. 11.19 (``What is a final rule?''), after public notice, as 
required by Sec. 11.38 (``What public comment procedures does FAA 
follow for Special Conditions?''), and become part of the type 
certification basis in accordance with Sec. 21.101(b)(2).
    Special conditions are initially applicable to the model for which 
they are issued. Should Gulfstream Aerospace Corporation apply at a 
later date for a supplemental type certificate to modify any other 
model included on the same type certificate to incorporate the same 
novel or unusual design feature, these special conditions would also 
apply to the other model under the provisions of Sec. 21.101(a)(1).

Novel or Unusual Design Features

    The EVS is novel or unusual technology because it places a raster * 
infrared image in the center of the pilot's regulated ``pilot 
compartment view,'' which must be free of interference, distortion, and 
glare that would adversely affect the performance of the pilot's normal 
duties. (*A ``raster'' image is typically a set of horizontal lines 
composed of individual pixels, used to form an image on a CRT or other 
screen.) The EVS/HUD system displays a raster image from a forward-
looking infrared (FLIR) camera on the previously approved Honeywell HUD 
2020 system. The EVS image is displayed with HUD symbology and overlays 
the forward outside view. Fundamentally, the combination of information 
seen by the pilot in the EVS image, and the visual information seen by 
the pilot through and around the image, must be as safe and effective 
as the pilot's view without EVS.
    Operationally, during an instrument approach, the EVS image is 
intended to supplement the pilot's ability to detect and identify 
``visual references for the intended runway,'' which are listed and 
required by Sec. 91.175(c)(3) (``Takeoff and landing under IFR'') to 
continue the approach below decision height. It may be possible to 
demonstrate whether, in certain conditions, the EVS can provide an 
image of such references, perhaps even better than the references can 
be seen through the window by the pilot without EVS. However, systems 
such as EVS, which use the infrared wavelength, sense the scene with 
distinctly different characteristics than a pilot's eyes do. An 
infrared sensor responds to apparent temperature differences in the 
scene and does not respond to contrasting colors and brightness like 
the pilot's eyes would. Visual features can appear significantly 
different to a pilot in the infrared image than they would with normal 
vision.
    While displaying the infrared image, the EVS also will partially 
interfere with the pilot's natural outside view. There is the potential 
for the image to improve the pilot's ability to detect and identify 
items of interest, yet, at the same time, the potential for it to 
interfere with the pilot compartment view. Section 25.773(a)(2) states:

    Each pilot compartment must be free of glare and reflection that 
could interfere with the normal duties of the minimum flight crew.

    The EVS image is displayed in the field of view required by 
Sec. 25.773, and may potentially interfere with the pilot's

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ability to see the actual outside scene through the forward window, 
particularly in the center of the forward field of view.
    The EVS raster image has more potential for interference with the 
pilot compartment view than stroke symbols also displayed on the HUD. 
Stroke symbology illuminates a small fraction of the total display area 
of the HUD. Without the raster image, the pilot can easily see around 
the symbology and the outside view is not unacceptably compromised. 
However, unlike stroke symbology, the EVS image illuminates most of the 
total display area of the HUD (approximately 30 degrees horizontally 
and 20 degrees vertically) with much greater potential interference 
with the pilot compartment view. The pilot cannot see around the raster 
image, but must see the outside scene through it.
    Additionally, unlike the pilot's external view, the EVS image is 
monochrome and two-dimensional, without depth cues. The quality of the 
EVS image and the level of EVS infrared sensor performance could depend 
significantly on the atmospheric and external light source conditions. 
Gain settings of the sensor, and brightness or contrast settings of the 
HUD, can significantly affect image quality. Certain system 
characteristics can create distracting and confusing display artifacts. 
Finally, because this is a sensor-based system that is intended to 
provide a conformal perspective corresponding with the outside scene, 
the potential for misalignment must be considered.
    Hence, criteria for each of the following need to be addressed:
     An acceptable degree of interference of the window or 
``window and HUD'' view;
     Potential image misalignment;
     Distortion; and
     The potential for pilot confusion or misleading 
information.
    Section 25.773 did not anticipate this type of technology, and the 
regulation currently is not considered to be adequate to address the 
specific issues related to an enhanced vision system. Therefore, the 
FAA has determined that, in addition to the requirements of 14 CFR part 
25, special conditions are needed to address requirements particular to 
the installation of an EVS.

Discussion

    Gulfstream Aerospace Corporation intends for the EVS to present an 
enhanced view that would aid the pilot, during the approach:
     To see and recognize external visual references that are 
required by Sec. 91.175(c), and
     To visually monitor the integrity of the approach, as 
described in FAA Order 6750.24D (``Instrument Landing System and 
Ancillary Electronic Component Configuration and Performance 
Requirements, `` dated March 1, 2000).
    Based on this functionality, users would seek to obtain operational 
approval to conduct approaches when the Runway Visual Range (RVR) is as 
low as 1,200 feet, including approaches to Type I runways. Gulfstream 
does not intend for the EVS imagery to be used either as a means of 
flight guidance, or as the substitution for the outside view while 
maneuvering the airplane during approach, landing, rollout, or takeoff.
    The FAA considers that EVS may be found acceptable for the 
following functions:
     Presenting an enhanced view that would aid the pilot 
during the approach.
     Displaying an image that the pilot can use to detect and 
identify the ``visual references for the intended runway'' required by 
Sec. 91.175(c)(3) to continue the approach with vertical guidance to 
100 feet height above touchdown (HAT).
    However, the FAA finds that it would not be appropriate to reduce 
the ceiling and visibility minima of the instrument approach procedure 
being used based on the use of EVS.
    Further, the FAA certification of EVS is limited as follows:
     The infrared-based EVS image will not be certified as a 
means to satisfy the requirements for descent below 100 feet HAT.
     The infrared-based EVS image will not be certified as a 
means to establish that flight visibility is consistent with the 
visibility condition prescribed in the standard instrument approach 
being used [see Sec. 91.175(c)(2)].
     The EVS imagery, alone, will not be certified either as 
flight guidance, or as a substitution for the outside view for 
maneuvering the airplane during approach, landing, rollout, or takeoff.
     The EVS may be used as a supplemental device during any 
phase of flight or operation in which its safe use has been 
established.
    Although the EVS image projected on the HUD can interfere with the 
pilot compartment view, contrary to Sec. 25.773, the FAA finds that an 
equivalent level of safety to that requirement may be possible with the 
combined view of the image and the outside scene that the pilot is able 
to see through the image. An EVS image may reduce the clear outside 
view of portions of the visual field, and yet, at the same time, may 
provide an enhanced image of that scene. The pilot must be able to use 
this combination of information seen in the image, and the natural view 
of the outside scene seen through the image, as safely and effectively 
as the pilot would use a Sec. 25.773-compliant pilot compartment view 
without an EVS image. This is the fundamental objective of the proposed 
special conditions. Compliance with these special conditions and other 
airworthiness requirements of part 25 does not constitute operational 
approval for use of EVS.
    The FAA intends to develop guidance material for use of the EVS 
that will cover operations, pilot qualification, and training.
    The FAA also intends to apply certification criteria, not as 
special conditions, for compliance with other Federal Aviation 
Regulations, including Sec. 25.1301 (``Equipment: Function and 
installation'') and Sec. 25.1309 (``Equipment, systems, and 
installations''). These criteria address certain image characteristics, 
installation, demonstration, and system safety.
    Image characteristics criteria include:
     Resolution,
     Luminance,
     Luminance uniformity,
     Low level luminance,
     Contrast variation,
     Display quality,
     Display dynamics (for example, jitter, flicker, update 
rate, and lag), and
     Brightness controls.
    Installation criteria address:
     Visibility and access to EVS controls, and
     Integration of EVS in the cockpit.
    The EVS demonstration criteria address the flight and environmental 
conditions that need to be covered.
    The FAA also intends to apply certification criteria relevant to 
high intensity radiated fields (HIRF) and lightning protection.
    A copy of these proposed means of compliance criteria may be 
obtained by sending a request to the following e-mail address: [email protected].

Applicability

    As discussed above, these proposed special conditions would apply 
to Gulfstream Model G-V airplanes modified by Gulfstream Aerospace. 
Should Gulfstream Aerospace apply at a later date for a supplemental 
type certificate to modify any other model included on the same type 
certificate to incorporate the same novel or unusual

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design feature, these special conditions would apply to that model as 
well under the provisions of Sec. 21.101(a)(1).

Conclusion

    This action affects only certain novel or unusual design features 
on the Gulfstream Model G-V airplanes modified by Gulfstream Aerospace. 
It is not a rule of general applicability and affects only the 
applicant who applied to the FAA for approval of these features on the 
airplane.

List of Subjects in 14 CFR Part 25

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.
    The authority citation for these proposed special conditions is as 
follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.

The Proposed Special Conditions

    Accordingly, the Federal Aviation Administration proposes the 
following special conditions as part of the supplemental type 
certification basis for the Gulfstream Model G-V airplanes modified by 
Gulfstream Aerospace:
    1. The EVS imagery on the HUD must not degrade the safety of 
flight, nor interfere with the effective use of outside visual 
references for required pilot tasks, during any phase of flight in 
which it is to be used.
    2. To avoid unacceptable interference with the safe and effective 
use of the pilot compartment view, the EVS device must meet the 
following requirements:
    2.a. The EVS design must minimize unacceptable display 
characteristics or artifacts (for example, noise, ``burlap'' overlay, 
running water droplets) that obscure the desired image of the scene, 
impair the pilot's ability to detect and identify visual references, 
mask flight hazards, distract the pilot, or otherwise degrade task 
performance or safety.
    2.b. Control of EVS display brightness must be sufficiently 
effective, in dynamically changing background (ambient) lighting 
conditions, to prevent full or partial blooming of the display that 
would distract the pilot, impair the pilot's ability to detect and 
identify visual references, mask flight hazards, or otherwise degrade 
task performance or safety. If automatic control for image brightness 
is not provided, it must be shown that a single manual setting is 
satisfactory.
    2.c. A readily accessible control must be provided that permits the 
pilot to immediately deactivate and reactivate display of the EVS image 
on demand.
    2.d. The EVS image on the HUD must not impair the pilot's use of 
guidance information nor degrade the presentation and pilot awareness 
of essential flight information displayed on the HUD, such as alerts, 
airspeed, attitude, altitude and direction, approach guidance, 
windshear guidance, TCAS resolution advisories, and unusual attitude 
recovery cues.
    2.e. The EVS image must be sufficiently aligned and conformal to 
both the external scene and conformal HUD symbology so as not to be 
misleading, cause pilot confusion, or increase workload.
    2.f. A HUD system modified to display EVS images must continue to 
meet all the requirements of the original approval.
    3. The safety and performance of the pilot tasks associated with 
the use of the pilot compartment view must be not be degraded by the 
display of the EVS image. Pilot tasks that must not be degraded by the 
EVS image include:
    3.a. Detection, accurate identification, and maneuvering, as 
necessary, to avoid traffic, terrain, obstacles, and other hazards of 
flight.
    3.b. Accurate identification and use of visual references required 
for every task relevant to the phase of flight.
    4. The use of EVS will not reduce the ceiling and visibility minima 
of the instrument approach procedure being used. The EVS may be found 
acceptable for the following functions:
    4.a. Presenting an image that would aid the pilot during the 
approach.
    4.b. Displaying an image that the pilot can use to detect and 
identify the ``visual references for the intended runway'' required by 
Sec. 91.175(c)(3) to continue the approach with vertical guidance to 
100 feet height above touchdown (HAT). Appropriate limitations must be 
included in the Operating Limitations section of the Airplane Flight 
Manual to prohibit the use of the EVS for functions not found to be 
acceptable.

    Issued in Renton, Washington, on March 8, 2001.
Vi L. Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-6531 Filed 3-15-01; 8:45 am]
BILLING CODE 4910-13-U