CAE SimuFlite 

 PO Box 619119 

 2929 W Airfield Drive 

 DFW Airport, TX 75261 

 United States

CAE Inc. Confidential and/or Proprietary Information 

July 25, 2011 

Docket Management Facility 

US Department of Transportation 

1200 New Jersey Avenue, SE 

West Building Ground Floor 

Room W12-140 

Washington, DC 20590 

Sent By Facsimile & Email 

Dear Sir/Madam: 

RE: Petition for Exemption to 14 CFR Part-60 Table C2A, Paragraph 4.b.1, 4.b.2, and 4.b.3. 

CAE Inc. respectfully submits this request for an exemption with respect to the requirement 

for a tolerance of 14 Code of Federal Regulations Part 60 Table C2A, paragraphs 4.b.1, 

4.b.2, and 4.b.3 which requires a geometric error between the image generator eye point and 

the pilot eye point to be less than 8°. 

The enclosure to this letter provides the details of the petition, in accordance with Title 

14 CFR section 11.81. The following summary is provided for the Federal Register in 

accordance with 14 CFR §11.81(f): 

“CAE Inc. respectfully submits the following request for an exemption to the tolerance 

requirements of 14 CFR Part 60, Continuous Field-of-View tests as stated in Table C2A 

paragraphs 4.b.1, 4.b.2 and 4.b.3. CAE seeks exemption to extend the requirement for 

the geometric error between the Image Generator eye point and the pilot eye point from 

‘8° or less’ to ‘12° or less’.” 

I trust that this correspondence will be to your satisfaction, and it satisfies the requirements of 

14 CFR §60.5; should you have any questions or require additional information please do not 

hesitate to contact the undersigned by email Itash.Samani@cae.com or telephone at (972) 

456-8078. 

Thank you for your consideration of this request. 

Sincerely, 

___________________________ 

Itash Samani, Head of Global FSTD Regulations 

Cc: Mr. Stephane Clement, Director Regulatory Affairs 
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CAE Inc. Confidential and/or Proprietary Information 

This petition contains the following elements: 

• Introduction (Extent of Relief) 

• Background on 14 CFR Part 60 

• Statement of Public Interest 

• Statement of no Adverse Effect on Safety 

• Conclusion 

 

The extent of relief CAE seeks, and the reason CAE seeks the relief 

14 CFR Part 60, objective test for demonstration of the Continuous Field-Of-View (Test Entry No’s: 

4.b.1; 4.b.2; and 4.b.3) requires that “Any geometric error between the Image Generator eye point 

and the pilot eye point must be 8° or less.” 

The Helicopter International Working Group (H-IWG) performing the work under the auspices of the 

Royal Aeronautical Society (RAeS) which is currently working on the development of the standards for 

the ICAO 9625 Revision 3 has reviewed the acceptable tolerance for this error to be 12°. 

CAE’s own technical and training analysis supports the H-IWG position and therefore under the 

provisions set forth in Title 14 Code of Federal Regulations (14 CFR) §11.81, CAE petitions the 

FAA to grant exemption from the tolerance requirement of 8°. In accordance with §11.81 (c), the 

extent of relief sought via this petition is limited to extending the tolerance beyond “8° or less” to

“12° or less”. 

As required by §11.81(d) and 11.81(e), it will be shown in the following technical assessment that 

granting of this petition for exemption will not adversely affect safety, and is in the "Public 

Interest." 

Per §11.81(h), CAE requests the privileges of this exemption be extended outside the United 

States. FAA has Bilateral Aviation Safety Agreements with a number of countries and a number 

of CAE simulators have been qualified under the BASA Flight Standards Agreements, Simulator 

Implementation Procedures (SIP). This extension of privileges is therefore necessary for 

operations based within foreign countries for equipment which has been qualified under FAA 14 

CFR Part 60 and in use under an FAA approved training program or for operations having 

bilateral agreements with the United States accepting FAA 14 CFR Part 60 as their standard for 

the qualification of Flight Simulation Training Equipment. 

Background on the Geometry Error Requirement of 14 CFR Part 60 

The change from the FAA Advisory Circular 120-63 standard to the 14 CFR Part 60 regulations for the 

qualification and use of Flight Simulation Training Devices with regards to helicopter simulators 

included the removal of the requirement for collimated display systems for rotorcraft simulators along

with the addition of a requirement for a maximum allowable geometric error. The relevant sections of 

both documents, as they apply to Level D simulators, are as follows: 

AC120-63, Appendix 1, Paragraph 4.d 

Continuous minimum collimated (or equivalent) visual field of view of 180 degrees horizontal 

and 60 degrees vertical available to each pilot. In addition, operational chin windows 

representative of those found in the helicopter model simulated are required. 

Part 60, Table C2A, Paragraph 4.b.3 

Continuous field-of-view of at least 176° horizontal and 56° vertical field-of-view for each pilot 

simultaneously. Any geometric error between the Image Generator eye point and the pilot eye 

point must be 8° or less. 

Note: This requirement did not exist in the previous FAA AC120-63 standard nor does it exist in 

the current JAR/EASA FSTD-H. 
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CAE Inc. Confidential and/or Proprietary Information 

The effect of these changes is to eliminate the requirement for collimation (allowing use of direct 

projection/dome displays) while limiting the allowable angular error seen by the pilot(s) that results from 

the removal of the collimation. 

Parallax Error 

The angular error in a dome display is a function of the distance between the design eyepoint (DEP, 

the position for which the system geometry has been optimized) and the pilot eyepoint as well as the 

distance from these eyepoint‘s to the dome surface. The error is also a function of which point in the

field of view (FOV) is being tested, and the modeled distance to the point of the scene in view, but 

assuming an eyepoint that is roughly centered fore/aft and up/down relative to the center of curvature of 

the dome the point of maximum error is generally for distant objects straight ahead of the eyepoint. The 

diagram below shows the error assuming that the DEP was selected to be the midway point between 

the PEP and CPEP rather than being located at the PEP or CPEP. Of course, it is always possible to 

compute the distortion from the PEP (effectively moving the DEP to overlay the PEP position), and 

hence have zero error from the PEP, but this roughly doubles the error from the CPEP. 

For the situation shown in the diagram the error can be computed as: 

error=atan(eyepoint_offset/dome_radius) 

Alternately, the maximum allowable lateral eyepoint offset for a given allowed error and dome radius 

can be computed as: 

 

eyepoint_offset = dome_radius * tan(error) 
 Page 4 of 5 July 25, 2011 

CAE Inc. Confidential and/or Proprietary Information 

The second formula is useful for determining which helicopter models can be supported by a given 

dome configuration. The resulting values are shown in the table below for a range of radii and allowable 

errors. It should be noted that moving the cockpit relative to the dome center provides the potential for 

increasing the distance from the eyepoint to the dome, and can therefore provide some flexibility in the 

maximum eyepoint offset that can be supported for a given allowable error and dome radius, but the 

table still provides useful guidelines for suitable display system configurations. 

Error Radius Radius Eyepoint offset 

degrees Feet Metres Inches mm 

8 8 2.44 13.49 343 

8 9 2.74 15.18 386 

8 10 3.05 16.86 428 

8 11 3.35 18.55 471 

8 12 3.66 20.24 514 

8 13 3.96 21.92 557 

8 14 4.27 23.61 600 

8 15 4.57 25.30 643 

10 8 2.44 16.93 430 

10 9 2.74 19.04 484 

10 10 3.05 21.16 537 

10 11 3.35 23.28 591 

10 12 3.66 25.39 645 

10 13 3.96 27.51 699 

10 14 4.27 29.62 752 

10 15 4.57 31.74 806 

12 8 2.44 20.41 518 

12 9 2.74 22.96 583 

12 10 3.05 25.51 648 

12 11 3.35 28.06 713 

12 12 3.66 30.61 777 

12 13 3.96 33.16 842 

12 14 4.27 35.71 907 

12 15 4.57 38.26 972 

These values can be compared to the lateral eyepoint offsets of typical helicopter types 

AIRCRAFT 

TYPE Eyepoint Offset Eyepoint Offset 

 mm 

CH53G 24 610 

UD-1D, AB205 22 559 

LYNX RBL 18.5 / LBL 17.52 RBL 470/ LBL 445 

BELL 412 22 559 

CH47 RBL 22 / LBL 21 

RBL 559 / LBL 

533 

MERLIN 23.62 600 

PUMA RBL 19.3 / LBL 19.7 

RBL 490 / LBL 

500 

S76 RBL 18 / LBL 17 

RBL 457 / LBL 

432 

UH- 24 610 
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CAE Inc. Confidential and/or Proprietary Information 

60/Blackhawk 

TH-57 

RBL 14.21 / LBL 

11.21 

RBL 361 / LBL 

285 

TH-67 

RBL 14.21 / LBL 

11.21 

RBL 361 / LBL 

285 

OH-58 

RBL 14.21 / LBL 

11.21 

RBL 361 / LBL 

285 

AH/MH-6 13.4 340 

A109 13.2 335 

AB139 21.7 550 

H92 22.0 559 

EC135 15.4 390 

NH90 24.8 630 

EC175 22 559 

How our request would benefit the public as a whole 

The FAA clearly recognized the benefits of direct projections systems to allow for more cost effective

solutions to building rotary wing FSTDs and with this in mind the consideration that larger domes are 

inherently more expensive to build (larger/heavier designs in turn driving motion system requirements,

more and/or brighter projectors required to meet brightness requirements) and to operate (larger facility 

requirements). It is therefore inherently preferable to use smaller domes where possible. Therefore this 

provides for the more cost effective build of these FSTDs, while still maintaining the high standards 

required performing the necessary training, and the public as a whole benefits from the fact that more

crews are able to complete such training due to affordability. 

Statement of no Adverse Effect on Safety 

There is no adverse effect on safety. The grant of exemption will allow for the most cost effective 

build of Flight Simulation Training Devices and therefore can only help towards better safety. 

Experiments performed by the RAeS IWG support the view that the expected errors, limited to 12° do 

not adversely affect the performance of maneuvers by either pilot. 

Conclusion: 

The grant of this exemption is in the public interest, it will allow the FAA to align the requirement 

for the geometric error to the standard recommended by the industry and global regulatory bodies 

participating in the RAeS IWG and will help towards reducing the cost of developing rotary wing 

simulators, which can only further help towards an improvement in the safety levels for rotary 

wing operations.