Exemption No. 10521 

UNITED STATES OF AMERICA 

DEPARTMENT OF TRANSPORTATION 

FEDERAL AVIATION ADMINISTRATION 

WASHINGTON, DC 20591 

In the matter of the petition of 

AMERICAN EUROCOPTER 

for an exemption from 14 CFR 

part 60 Appendix C, Table C2A 

Title 14, Code of 

Federal Regulations 

Regulatory Docket No. FAA-2011-0824 

GRANT OF EXEMPTION 

By letter dated August 4, 201 1, Mr. Tim McAdams, Manager, American Eurocopter, 2701 

Forum Drive, Grand Prairie, TX 75052 petitioned the Federal Aviation Administration (FAA) 

on behalf of American Eurocopter Flight Simulation Center (AEFSC) for an exemption from 

part 60, Appendix C, Table C2A, 4.b.3 ofTitle 14, Code of Federal Regulations (14 CFR). 

The proposed exemption, if granted, would permit a geometric error of up to 12 degrees 

between the image generator (IG) eye point and the pilot eye point for the Eurocopter (EC) 

175 Level D full flight simulator (FFS). 

The petitioner requests relief from the following regulation: 

Part 60, Continuous Field-of-View (Fo V) tests as stated in Table C2A paragraph 4.b.3, 

require any geometric error between the image generator eyepoint and the pilot 

eyepoint to be go or Jess. 

The petitioner supports its request with the following information: 

The petitioner states American Eurocopter is seeking an exemption to 14 CFR part 60, 

Appendix C, Table C2A, 4.b.3, specifically, allowing a geometric error greater than go_ In 

order to produce a realistic helicopter training experience, the pilot must be able to accurately 

hover in close proximity to objects and landing areas. To design a visual system that 

realistically replicates this requirement requires that the dome be as close as possible to the 

pilot. However, moving the dome closer increases the geometric error. The petitioner believes 

AFS-11-413-E 
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that the trade off of accepting a higher geometric error in order to provide an enhanced hover 

and landing experience greatly improves the helicopter training experience. This exemption 

will allow an improved design that improves training for hovering and close proximity to 

objects operations. Improved training will significantly enhance safety. 

A technical description follows: 

EC175 Full Flight Simulator, Level-D 

Technical Note 

Visual Display System (VDS) 

Parallax Error & Dome Screen Size. 

Introduction 

It is accepted that wide visual fields of view, both horizontal and vertical, with coverage for 

peripheral view, look down on side-door window and chin window areas, greatly contribute 

to simulator acceptance by pilots and training effectiveness. As for today's technology status, 

the only feasible solution for FoV in excess of210° x 60° is direct projection on a dome 

screen, which combined with adequate scene content and texture details also provide for a 

highly accurate perception of height above ground and ground speed magnitude and direction, 

as required for ground operations and low level hover and flight tasks. 

For multi-crew helicopters, a significant contribution to the VDS error is the so called 

parallax error to distant objects because of different crewmember and Image 

Generator/Projection System eye point reference positions. The VDS typically includes a 

switching capability to set the IG viewpoint to the pilot-flying eye point for critical tasks so 

the parallax error is effectively cancelled out (to the expense of a higher parallax error for the 

pilot-not-flying). For general tasks, or when both pilot and copilot are involved, a center view 

is selected (mid-point between design eye point positions) so the parallax error for both crew 

members simultaneously is minimized. 
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Conclusions 

There is no single VDS solution that is optimal from all points of view at the same time. As a 

result, there will always be a trade-off to achieve regulatory compliance, while meeting 

training aspects and practical simulator design considerations. 

The proposed VDS design provides an excellent coverage ofECI75 cockpit FoV and pretty 

good height perception for ground operations and low level hovers and flight tasks. While in 

strict sense, 3.25m (10.7ft) dome radius parallax error for distant objects in center view is 

over the current 8° requirement by 14 CPR part 60, it is still kept within practical acceptable 

values, and in any case, view point switching allows for pilot-flying error cancellation for 

critical flight tasks. 

The petitioner believes the trade-off of accepting a higher geometric error in order to provide 

an enhanced hover and landing experience greatly improves the helicopter training 

experience. The petitioner states a grant of exemption would result in a better trained pilot. 

Better training enhances safety and safe helicopter operations are a substantial benefit to the 

public as a whole. 

A summary of the petition was published in the Federal Register on October 4, 20II 

(76 FR 6I473). No comments were received. 

The FAA's analysis is as follows: 

The FAA has fully considered the petitioner's request and supporting information. The FAA 

finds that a grant of exemption would be in the public interest and would provide a level of 

safety equivalent to that provided by the current regulations. 

The FAA finds that there is no single visual display system (VDS) solution that is optimal, for 

purposes of helicopter simulator visual systems, from all points of view at the same time. As 

a result, there will be a trade-off to achieve regulatory compliance and training capabilities, 

while meeting practical simulator design considerations. In a strict sense, the computed 

geometric error for distant objects in center view may exceed the current go requirement by 

I4 CFR part 60 for typical VDS dome sizes of wider bodied helicopter simulators (such as the 

Eurocopter ECI75). It is recognized, however, that the geometric error may still be kept 

within subjectively acceptable values through optimizing the design eye point position and 

view point switching that allows for pilot-flying error cancellation for critical flight tasks. 
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As the petitioner has remarked, the FAA is aware of and has participated in the ongoing work 

of the Royal Aeronautical Society in proposing updates to the ICAO 9625 standards for 

helicopter simulators. While the ICAO document has not yet been completed, the FAA 

agrees with the conclusion that minor deviations from the go parallax error tolerance will have 

minor effects that are limited to specific training tasks which may be susceptible to parallax 

error (such as running landings). These effects can easily be mitigated through eye point 

switching and/or training task restrictions on flight simulation training device (FSTD) use as 

determined through subjective assessment. 

Furthermore, the FAA also agrees with the petitioner's argument that height perception of 

objects in close proximity is a common complaint ofFSTD users with collimated VDS 's 

(required for FSTDs qualified prior to part 60 becoming effective) and could also be 

problematic on a direct view VDS with a large dome radius. Since much of a helicopter 

pilot's eye is focused on objects in close proximity during critical training maneuvers (such as 

hover and landing), improvements in height perception cues are likely to improve the overall 

training experience and are worth the relatively minor tradeoff in geometric error. 

The FAA agrees with the assertion that allowing a geometric error greater than go will allow 

for an improved design that improves training for hovering and close proximity to objects 

operations. Improved training can significantly enhance safety. 

The FAA's Decision 

In consideration of the foregoing, I find that a grant of exemption is in the public interest. 

Therefore, pursuant to the authority contained in 49 U.S.C. §§ 40113 and 44701, delegated to 

me by the Administrator, American Eurocopter Flight Simulation Center is granted an 

exemption from 14 CFR part 60, Continuous Field-of-View tests as stated in Table C2A 

paragraphs 4.b.3 to the extent necessary to allow (AEFSC) to manufacture and obtain FAA 

qualification of its Level D FSTD. This grant of exemption is further subject to the following 

conditions and limitations: 

Conditions and Limitations 

1. A geometric error of no greater than 12° is allowed subject to evaluation by a 

National Simulator Program (NSP) Aviation Safety Inspector by conducting ground 

and flight maneuvers to validate the geometric/parallax error does not negatively 

affect qualified training, testing, or checking tasks. 
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2. If the objective/subjective testing is successful, the NSP Inspector will make a 

recommendation to the National Simulator Program Manager (NSPM) for final 

approval. 

3. Any training maneuver found to not be subjectively acceptable due to 

geometric/parallax error will be task restricted on the FSTD's Statement of 

Qualification as determined appropriate by the NSPM. 

This exemption terminates on May 31 , 2014, unless sooner superseded or rescinded. 

Issued in Washington, D.C., on April30, 2012. 

JohnS. Duncan 

Deputy Director, Flight Standards 

Service