[Federal Register Volume 70, Number 100 (Wednesday, May 25, 2005)]
[Rules and Regulations]
[Pages 29937-29940]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-10412]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM303; Special Conditions No. 25-288-SC]


Special Conditions: Bombardier Aerospace Models BD-700-1A10 and 
BD-700-1A11 Global Express Airplanes, Enhanced Flight Visibility System 
(EFVS)

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

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SUMMARY: These special conditions are issued for the Bombardier 
Aerospace Models BD-700-1A10 and BD-700-1A11 Global Express airplanes. 
These airplanes, as modified by Bombardier Aerospace Corporation, will 
have an Enhanced Flight Visibility System (EFVS). The EFVS is a novel 
or unusual design feature which consists of 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: Effective Date: May 12, 2005.

FOR FURTHER INFORMATION CONTACT: Dale Dunford, FAA, ANM-111, Airplane 
and Flight Crew Interface, Transport Airplane Directorate, Aircraft 
Certification Service, 1601 Lind Avenue SW., Renton, Washington 98055-
4056; telephone (425) 227-2239; fax (425) 227-1320; e-mail: 
[email protected].

SUPPLEMENTARY INFORMATION:

Background

    On February 26, 2003, Bombardier Aerospace, applied for an 
amendment to the type certificate to modify Bombardier Model BD-700-
1A10 and BD-700-1A11 Global Express airplanes. The Model BD-700-1A10 is 
a transport category airplane certified to carry a maximum of 19 
passengers and a minimum of 2 crew members. The Model BD-700-1A11 is a 
smaller version of the BD-700-1A10. The modification involves the 
installation of an Enhanced Flight Vision System (EFVS). This system 
consists of a Thales HUD system, modified to display FLIR imagery, and 
a FLIR camera.
    The electronic infrared image displayed between the pilot and the 
forward windshield represents a novel or unusual design feature in the 
context of 14 CFR 25.773. Section 25.773 was not written in 
anticipation of such technology. The electronic image has the potential 
to enhance the pilot's awareness of the terrain, hazards, and airport 
features. At the same time, the image may partially obscure the pilot's 
direct outside compartment view. Therefore, the FAA needs adequate 
safety standards to evaluate the EFVS to determine that the imagery 
provides the intended visual enhancements without undue interference 
with the pilot's outside compartment view. The FAA's intent is that the 
pilot will be able to use the combination of information seen in the 
image and the natural view of the outside seen through the image as 
safely and effectively as a Sec.  25.773-compliant pilot compartment 
view without an EVS image.
    Although the FAA has determined that the existing regulations are 
not adequate for certification of EFVSs, it believes that EFVSs could 
be certified through application of appropriate safety criteria. 
Therefore, the FAA has determined that special conditions should be 
issued for certification of EFVS to provide a level of safety 
equivalent to that provided by the standard in Sec.  25.773.

    Note: The term ``enhanced vision system (EVS)'' has been 
commonly used to refer to a system comprised of a head up display, 
imaging sensor(s), and avionics interfaces that displayed the sensor 
imagery on the HUD and overlaid it with alpha-numeric and symbolic 
flight information. However, the term has also been commonly used in 
reference to systems which displayed the sensor imagery, with or 
without other flight information, on a head down display. To avoid 
confusion, the FAA created the term ``enhanced flight visibility 
system (EFVS)'' to refer to certain EVS systems that meet the 
requirements of the new operational rules'in particular the 
requirement for a HUD and specified flight information'and can be 
used to determine ``enhanced flight visibility.'' EFVSs can be 
considered a subset of systems otherwise labeled EVSs.


    On January 9, 2004, the FAA published revisions to operational 
rules in 14 CFR parts 1, 91, 121, 125, and 135 to allow aircraft to 
operate below certain altitudes during a straight-in instrument 
approach while using an EFVS to meet visibility requirements.
    Prior to this rule change, the FAA issued Special Conditions 25-
180-SC, which approved the use of an EVS on Gulfstream Model G-V 
airplanes. These special conditions addressed the requirements for the 
pilot compartment view and limited the scope of the

[[Page 29938]]

intended functions permissible under the operational rules at the time. 
The intended function of the EVS imagery was to aid the pilot during 
the approach and allow the pilot to detect and identify the visual 
references for the intended runway down to 100 feet above the touchdown 
zone. However, the EVS imagery alone was not to be used as a means to 
satisfy visibility requirements below 100 feet.
    The recent operational rule change expands the permissible 
application of certain EVSs that are certified to meet the new EFVS 
standards. The new rule will allow the use of EFVSs for operation below 
the Minimum Descent Altitude (MDA) or Decision Height (DH) to meet new 
visibility requirements of Sec.  91.175(l). The purpose of this special 
condition is not only to address the issue of the ``pilot compartment 
view'' as was done by 25-180-SC, but also to define the scope of 
intended function consistent with Sec.  91.175(l) and (m).

Type Certification Basis

    Under the provisions of 14 CFR 21.101, Bombardier Aerospace must 
show that the Bombardier Aerospace Model BD-700-1A10 and BD-700-1A11 
Global Express airplanes, as modified, comply with the regulations in 
the U.S. type certification basis established for those airplanes. The 
U.S. type certificate basis for the airplanes is established in 
accordance with 14 CFR 21.21, 14 CFR 21.17, and the type certification 
application date. The U.S. type certification basis for these model 
airplanes is listed in Type Certificate Data Sheet No. T00003NY.
    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 Bombardier Global Express 
airplanes modified by Bombardier Aerospace because of a novel or 
unusual design feature, special conditions are prescribed under the 
provisions of 14 CFR 21.16.
    Special conditions, as appropriate, are issued in accordance with 
14 CFR 11.19 after public notice, as required by 14 CFR 11.38, and 
become part of the type certification basis in accordance with 14 CFR 
21.101(b)(2).
    Special conditions are initially applicable to the model for which 
they are issued. Should Bombardier 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 
design feature, these special conditions would also apply to the other 
model under the provisions of 14 CFR 21.101(a)(1).

Novel or Unusual Design Features

    The EFVS is a novel or unusual design feature, because it projects 
a video image derived from a FLIR camera through the HUD. The EFVS 
image is projected in the center of the ``pilot compartment view,'' 
which is governed by Sec.  25.773. The image is displayed with HUD 
symbology and overlays the forward outside view. Therefore, Sec.  
25.773 does not contain appropriate safety standards for the EFVS 
display.
    Operationally, during an instrument approach, the EFVS image is 
intended to enhance the pilot's ability to detect and identify ``visual 
references for the intended runway'' [see Sec.  91.175(l)(3)] to 
continue the approach below decision height or minimum descent 
altitude. Depending on atmospheric conditions and the strength of 
infrared energy emitted and/or reflected from the scene, the pilot can 
see these visual references in the image better than he or she can see 
them through the window without EFVS.
    Scene contrast detected by infrared sensors can be much different 
from that detected by natural pilot vision. On a dark night, thermal 
differences of objects which are not detectable by the naked eye will 
be easily detected by many imaging infrared systems. On the other hand, 
contrasting colors in visual wavelengths may be distinguished by the 
naked eye but not by an imaging infrared system. Where thermal contrast 
in the scene is sufficiently detectable, the pilot can recognize shapes 
and patterns of certain visual references in the infrared image. 
However, depending on conditions, those shapes and patterns in the 
infrared image can appear significantly different than they would with 
normal vision. Considering these factors, the EFVS image needs to be 
evaluated to determine that it can be accurately interpreted by the 
pilot.
    The image may improve the pilot's ability to detect and identify 
items of interest. However, the EFVS needs to be evaluated to determine 
that the imagery allows the pilot to perform the normal duties of the 
flight crew and adequately see outside the window through the image, 
consistent with the safety intent of Sec.  25.773(a)(2).
    Compared to a HUD displaying the EFVS image and symbology, a HUD 
that only displays stroke-written symbols is easier to see through. 
Stroke symbology illuminates a small fraction of the total display area 
of the HUD, leaving much of that area free of reflected light that 
could interfere with the pilot's view out the window through the 
display. However, unlike stroke symbology, the video image illuminates 
most of the total display area of the HUD (approximately 30 degrees 
horizontally and 25 degrees vertically) which is a significant fraction 
of the pilot compartment view. The pilot cannot see around the larger 
illuminated portions of the video image, but must see the outside scene 
through it.
    Unlike the pilot's external view, the EFVS image is a monochrome, 
two-dimensional display. Many, but not all, of the depth cues found in 
the natural view are also found in the image. The quality of the EFVS 
image and the level of EFVS infrared sensor performance could depend 
significantly on conditions of the atmospheric and external light 
sources. The pilot needs adequate control of sensor gain and image 
brightness, which can significantly affect image quality and 
transparency (i.e., the ability see the outside view through the 
image). Certain system characteristics could 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 system must be able to ensure 
accurate alignment.
    Hence, there need to be safety standards for each of the following 
factors:
     An acceptable degree of image transparency;
     Image alignment;
     Lack of significant distortion; and
     The potential for pilot confusion or misleading 
information.
    Section 25.773--Pilot Compartment View, specifies that ``Each pilot 
compartment must be free of glare and reflection that could interfere 
with the normal duties of the minimum flight crew * * *.'' In issuing 
Sec.  25.773, the FAA did not anticipate the development of EFVSs and 
does not consider Sec.  25.773 to be adequate to address the specific 
issues related to such a system. Therefore, the FAA has determined that 
special conditions are needed to address the specific issues particular 
to the installation and use of an EFVS.

Discussion

    The EFVS is intended to function by presenting an enhanced view 
during the approach. This enhanced view would help the pilot to see and 
recognize external visual references, as required by Sec.  91.175(l), 
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).

[[Page 29939]]

    Based on this approved functionality, users would seek to obtain 
operational approval to conduct approaches--including approaches to 
Type I runways--in visibility conditions much lower than those for 
conventional Category I.
    The purpose of these special conditions is to ensure that the EFVS 
to be installed can perform the following functions:
     Present an enhanced view that would aid the pilot during 
the approach.
     Provide enhanced flight visibility to the pilot that is no 
less than the visibility prescribed in the standard instrument approach 
procedure.
     Display an image that the pilot can use to detect and 
identify the ``visual references for the intended runway'' required by 
Sec.  91.175(l)(3) to continue the approach with vertical guidance to 
100 feet height above the touchdown zone elevation.
    Depending on the atmospheric conditions and the particular visual 
references that happen to be distinctly visible and detectable in the 
EFVS image, these functions would support its use by the pilot to 
visually monitor the integrity of the approach path.
    Compliance with these special conditions does not affect the 
applicability of any of the requirements of the operating regulations 
(i.e., 14 CFR parts 91, 121, and 135). Furthermore, use of the EFVS 
does not change the approach minima prescribed in the standard 
instrument approach procedure being used; published minima still apply.
    The FAA certification of this EFVS is limited as follows:
     The infrared-based EFVS image will not be certified as a 
means to satisfy the requirements for descent below 100 feet height 
above touchdown (HAT).
     The EFVS may be used as a supplemental device to enhance 
the pilot's situational awareness during any phase of flight or 
operation in which its safe use has been established.
    An EFVS image may provide an enhanced image of the scene that may 
compensate for any reduction in the clear outside view of the visual 
field framed by the HUD combiner. 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 special 
conditions.
    The FAA will also apply additional certification criteria, not as 
special conditions, for compliance with related regulatory 
requirements, such as 14 CFR 25.1301 and 14 CFR 25.1309. These 
additional criteria address certain image characteristics, 
installation, demonstration, and system safety.
    Image characteristics criteria include the following:
     Resolution,
     Luminance,
     Luminance uniformity,
     Low level luminance,
     Contrast variation,
     Display quality,
     Display dynamics (e.g., jitter, flicker, update rate, and 
lag), and
     Brightness controls.
    Installation criteria address visibility and access to EFVS 
controls and integration of EFVS in the cockpit.
    The EFVS 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.

Discussion of Comments

    Notice of proposed special conditions No. 25-05-02 for the 
Bombardier Aerospace Models BD-700-1A10 and BD-700-1A11 Global Express 
Airplanes was published in the Federal Register dated March 30, 2005 
(70 FR 16161). Three public comments were received, one of which 
indicated full agreement with the special conditions.
    Two commenters disagreed with the sentence in the Discussion 
section of the NPRM which states, ``Based on this functionality, users 
would seek to obtain operational approval to conduct approaches--
including approaches to Type I runways--when the Runway Visual Range is 
as low as 1,200 feet.'' Both commenters recommended that the FAA delete 
this sentence, because a visibility limit of 1200 feet RVR is 
inconsistent with the recent change to 14 CFR 91.175 for EFVS. For part 
91 operators, there are no explicit reported visibility limitations. 
The FAA agrees with this suggestion.
    The sentence was meant to describe the visibility conditions in 
which EFVS could be used for an approach. In other words, 1,200 feet 
RVR was intended not as an operational limit, but as an example of the 
low visibilities that might be encountered during Category I approaches 
while using EVFS. These visibility conditions could be much lower than 
those for conventional Category I approaches.
    The FAA has revised the sentence to avoid the interpretation that 
it is meant to establish operational limitations or restrictions. This 
sentence now states:
    ``Based on this approved equipment functionality, users would seek 
to obtain operational approval to conduct approaches--including 
approaches to Type I runways--in visibility conditions much lower than 
for conventional Category I.''
    Because none of the comments suggested any changes to the special 
conditions themselves, they remain unchanged.

Applicability

    As discussed above, these special conditions are applicable to 
Bombardier Aerospace Models BD-700-1A10 and BD-700-1A11 Global Express 
airplanes. Should Bombardier 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 design 
feature, these special conditions would apply to that model as well.
    Under standard practice, the effective date of final special 
conditions would be 30 days after the date of publication in the 
Federal Register. However, as the certification date for the Bombardier 
Aerospace Models BD-700-1A10 and BD-700-1A11 Global Express airplanes 
is imminent, the FAA finds that good cause exists to make these special 
conditions effective upon issuance.

Conclusion

    This action affects only certain novel or unusual design features 
on the Bombardier Aerospace Models BD-700-1A10 and BD-700-1A11 Global 
Express airplane, as modified by Bombardier Aerospace. It is not a rule 
of general applicability and affects only the applicant which 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.

0
The authority citation for these special conditions is as follows:

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

The Special Conditions

0
Accordingly, pursuant to the authority delegated to me by the 
Administrator, the following special conditions are issued as part of 
the amended type certification basis for Bombardier Aerospace Models 
BD-700-1A10 and BD-700-1A11 Global Express airplanes, modified by 
Bombardier Aerospace:
    1. The EFVS imagery on the HUD must not degrade the safety of 
flight or interfere with the effective use of outside visual references 
for required

[[Page 29940]]

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 EFVS device must meet the 
following requirements:
    a. The EFVS design must minimize unacceptable display 
characteristics or artifacts (e.g. 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.
    b. Control of EFVS 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 for the range of lighting conditions encountered during a 
time-critical, high workload phase of flight (e.g., low visibility 
instrument approach).
    c. A readily accessible control must be provided that permits the 
pilot to immediately deactivate and reactivate display of the EFVS 
image on demand.
    d. The EFVS image on the HUD must not impair the pilot's use of 
guidance information or 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, or unusual attitude 
recovery cues.
    e. The EFVS image and the HUD symbols--which are spatially 
referenced to the pitch scale, outside view and image--must be scaled 
and aligned (i.e., conformal) to the external scene. In addition, the 
EFVS image and the HUD symbols--when considered singly or in 
combination--must not be misleading, cause pilot confusion, or increase 
workload. There may be airplane attitudes or cross-wind conditions 
which cause certain symbols (e.g., the zero-pitch line or flight path 
vector) to reach field of view limits, such that they cannot be 
positioned conformally with the image and external scene. In such 
cases, these symbols may be displayed but with an altered appearance 
which makes the pilot aware that they are no longer displayed 
conformally (for example, ``ghosting'').
    f. A HUD system used to display EFVS images must, if previously 
certified, continue to meet all of 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 EFVS image. These tasks include the following:
    a. Detection, accurate identification and maneuvering, as 
necessary, to avoid traffic, terrain, obstacles, and other hazards of 
flight.
    b. Accurate identification and utilization of visual references 
required for every task relevant to the phase of flight.
    4. Compliance with these special conditions will enable the EFVS to 
be used during instrument approaches in accordance with 14 CFR 
91.175(l) such that it may be found acceptable for the following 
intended functions:
    a. Presenting an image that would aid the pilot during a straight-
in instrument approach.
    b. Enabling the pilot to determine that the ``enhanced flight 
visibility,'' as required by Sec.  91.175(l)(2) for descent and 
operation below minimum descent altitude/decision height (MDA)/(DH).
    c. Enabling the pilot to use the EFVS imagery to detect and 
identify the ``visual references for the intended runway,'' required by 
14 CFR 91.175(l)(3), to continue the approach with vertical guidance to 
100 feet height above touchdown zone elevation.
    5. Use of EFVS for instrument approach operations must be in 
accordance with the provisions of 14 CFR 91.175(l) and (m). Appropriate 
limitations must be stated in the Operating Limitations section of the 
Airplane Flight Manual to prohibit the use of the EFVS for functions 
that have not been found to be acceptable.

    Issued in Renton, Washington, on May 12, 2005.
Jeffrey Duven,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 05-10412 Filed 5-24-05; 8:45 am]
BILLING CODE 4910-13-P