(A) The lock and its warning, if separate from the lock, should be easily discernable during both day and night operations. Consider the color, location, shape, and accessibility of the device, ease of removal by a seated pilot, and legibility of any placards, etc.
(B) The system operation should be obvious. It should only be possible to install the lock such that the warning placard is properly displayed.
(C) When engaged, the lock design should limit the operation of the rotorcraft so that the pilot receives unmistakable warning in the cockpit before takeoff by an effective means such as:
(1) preventing the application of sufficient engine power to attempt takeoff,
(2) preventing or changing a method of grasping or holding a primary control such as the cyclic or collective, or
(3) use of an audio warning device that cannot be disengaged.
(D) For rotorcraft with separate locks for collective and cyclic, where one lock is removable independently of the other, each lock should independently meet these criteria.
(iii) Section 29.771. This regulation correlates with most of the other HF - related regulations, particularly in situations where a pilot may allocate attention to a particular system or task at the expense of flying the rotorcraft. Applicants should identify aspects of the pilot-rotorcraft interface that might require significant or sustained concentration or physical effort which can lead to distraction and fatigue. Many factors can affect concentration and fatigue, such as noise, vibration, seat comfort, excessive control forces, and poorly designed displays, controls, or pilot-system interfaces.
Methods of compliance should focus on evaluation procedures that examine potential concentration demands and sources of fatigue for the flight crew. Some issues that can contribute to unreasonable concentration or fatigue are:
(A) Pilot-system interface. Interface design can potentially result in a large concentration trap. Interfaces that require substantial heads-down time in rotorcraft without stability augmentation systems can lead to the rotorcraft deviating from the pilot’s intended flight path. The system’s ability to support the pilot regarding input , cross-check, error identification, and recovery contributes to the attention resources the pilot uses and resulting concentration. Evaluations on a bench or simulator where the system interface is accurately portrayed can help identify potential issues. Flight evaluation will also provide valuable information regarding the design and pilot’s ability to work with that design.
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AC 29-2C, Chg 7 2/4/2016 (B) Display design. A number of factors associated with display design can ultimately affect concentration and fatigue. Displays that are difficult to read or contain poorly organized information, or lack necessary information, result in greater demands on pilot attention and concentration. Conduct evaluations under operationally representative scenarios to assess the effectiveness and usability of the displays.
(C) Cockpit and system control design and function. The ease of identification, accessibility, and usability of cockpit controls can affect the level of pilot concentration. Conduct evaluations to ensure all cockpit controls are easy to identify, access, and operate as required in flight. New control interfaces, such as touch pads or voice-command, should be evaluated in as many operational environments as possible to assess the pilot’s ability to perform tasks requiring their use.
(D) Pilot seats. Poorly designed seats have the potential to create fatigue.
Evaluate seats to determine if they contribute a significant amount of fatigue. Conduct these assessments using test participants and gathering subjective data. Conduct assessments based upon the expected average length of flight time the pilot remains in the seat, for a typical flight for the rotorcraft under evaluation. Subjective comments should be solicited from test participants concerning muscle tension, “hotspots” (areas where harder body contact is experienced), and body soreness or discomfort. Lateral support in the seat pan and lumbar support in the seat back have been used to increase seat comfort.
(E) Cockpit environmental control. Consider sufficient heating and cooling ability along with adequate ability to defrost or defog windscreens.
(iv) Section 29.773(a)(1). There must be sufficient external vision to enable the pilot to safely fly and control the rotorcraft. The design must provide a level of safety that ensures adequate external vision to see and avoid traffic and other obstacles in the environment. Consider any optical distortions in the windshield or canopy, especially in the prime viewing areas, which may degrade external viewing. For additional information, section 29.773 of this AC.
(A) The capability to provide an adequate view of the external environment is essential for safe operation. Applicants should consider defining an eye reference point in the design that will account for the range of expected pilot physical dimensions.
Conduct evaluations with individuals that represent a range of different human physical dimensions. Consider seat adjustment capability as it accommodates the range of expected pilot physical dimensions. Give particular attention to the size and location of rotorcraft structures that may obstruct the external view. Section 29.773 of this AC contains a cockpit visibility diagram showing the horizontal and vertical obstruction limits applicable to pilot visibility.
(B) Reflections. There should be no compromise of vision outside the cockpit by reflections from either internal or external lighting sources. Assess reflections from instrument and panel lighting as to their effect on pilot external view.
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Refer to section 29.773 of this AC for the area of the pilot compartment field of view that should be free from obstruction. Reflections appearing in this area should be blocked or otherwise diminished. Ensure that reflections do not affect outside visibility looking cross-cockpit. If possible, use full scale mockups to assess night lighting reflections to reduce program risk by identifying potential problem areas early. Assess the effect of cabin lighting on reflections in the pilot’s view area. Consider the use of curtains or other modifications to eliminate reflections from the aft cabin.
(C) Sunlight reflecting off instruments, display faces, and other cockpit structures will affect the pilot’s performance. Blocking or shading features may need to be included in the design. Additionally, check to ensure instruments, indicators, and displays are readable in all lighting conditions.
(D) Glare from instrument lighting can cause pilot performance issues.
Light balance and instrument lighting design should allow the pilot to illuminate all instruments and panels without having to adjust for glare. External lights can also create glare if the rotorcraft windows and windscreen scatter light entering the cockpit.
Assess for glare in both night and day environments. Assess the cockpit in all potential lighting conditions with sun at all angles including dawn or dusk conditions, with the sun near the horizon, higher sun angles (both in front, behind, and directly overhead of the rotorcraft), and during night conditions (both dark night and moonlit conditions). In addition, evaluate the effect various internal lighting selections and levels have on readability and usability of rotorcraft equipment and systems and the ability to see outside the cockpit.
(v) Section 29.777.
(A) Section 29.777(a). This regulatory provision addresses the usability of a control from a location and identification perspective. The location of a control can significantly affect the pilot’s ability to identify the control easily, the ease and convenience of operation of the control, confusion as to the control's operation, and an inadvertent operation of that control. Several techniques can aid in control identification and use. The size, shape, color, configuration, and method of operation can discriminate between controls and aid in control identification. Consider these other design related characteristics, relative to the control's location, when evaluating control identification and use. Unless its function and method of operation are obvious, a control must be labeled in accordance with § 29.1555. The suggested analyses and evaluation procedures described for showing compliance with § 29.671 are also applicable and recommended for this regulation.
(B) Section 29.777(b). This regulatory provision addresses the capability to operate a control through its full range of motion, considering potential interference from clothing and cockpit structures. This assessment can be accomplished simultaneously with the assessment for § 29.785(c) if the pilot is strapped into the seat wearing the lap belt and shoulder harness. Refer to section 29.777, paragraph b. of this AC. It is important to conduct evaluations using individuals representing a range of Page MG 20 - 15
AC 29-2C, Chg 7 2/4/2016 potential user physical dimensions and users wearing different apparel, such as long sleeved shirts, jackets, and gloves. Applicants may use analytical methods, such as computer modeling of the cockpit or flight deck and the pilots, for early problem identification and risk reduction. Regardless of the analytical models used, demonstrate compliance in either a high fidelity mockup, that accurately represents the actual rotorcraft, or in an actual rotorcraft. Although the regulation requires compliance for a certain range of pilot heights, consider also using individuals from a fifth percentile female and a 95th percentile male body stature. Consider using individuals that have a range of arm reach and seating statures within the selected population.
(vi) Section 29.785. This regulation is related to § 29.777(b). Section
29.785(c) requires that the restraint system allows crewmembers to perform "functions necessary for flight operations” while restrained by the safety belt and shoulder harness.
The discussion and suggested evaluation procedures for § 29.777(b) of this AC are applicable and should be used for finding compliance with this regulation as well, with the exception that evaluations must be conducted with crewmembers seated with safety belts and shoulder harnesses fastened. Additionally, evaluators should only assess the capability to perform functions necessary for flight operations. The certification plan should include a list of those cockpit functions necessary for flight operations, under normal and abnormal conditions. As in § 29.777(b) above, consider using individuals from a fifth percentile female and a 95th percentile male body size to assess compliance.
(vii) Section 29.1301. This regulation has broad implications and addresses a wide range of design and operational considerations. An important aspect of this regulation that can significantly affect the evaluation and finding of compliance is the interpretation of the "intended function" of a system. The system’s intended function is typically determined by assessing the design, functional capability, and operational use of the system. Applicants will generally provide this information for certification purposes. Applicants should work cooperatively with the certification authori ty so that the “intended function” of a system is accurate, reliable, realistic, and acceptable.
Therefore, it is important that the certification team assess the design, functional capability, and use of the system and compare that with the description of the intended function.
(A) Section 29.1301(a). The use of performance- based criteria should be used in determining that a system is of a kind and design appropriate to its intended function. Applicants should consider the complexity of the system in determining the test requirements. For concerns pertaining to the pilot-vehicle interface, the evaluation should investigate the capability of the pilot to perform related tasks adequately.
Performance measurements such as time-to-perform, number of inputs, accuracy, comprehension, awareness of system state and performance, and perceived workload may be collected to assess compliance. Evaluations should be conducted using operationally representative scenarios. Simulation may be used to verify that properly trained pilots can adequately perform all tasks using the system. Finally, flight tests can be used to investigate specific normal and abnormal operational scenarios.
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(B) Section 29.1301(b). This part of the regulation pertains to proper labeling of cockpit equipment for identification, functionality, and operating limitations, usually accomplished by placing a tag or label on the outside of the equipment. The labeling of any associated controls must comply with § 29.1555.
(viii) Section 29.1321.
(A) Section 29.1321(a). This regulatory provision does not specify the location in the instrument panel of flight, navigation, and powerplant instrument in transport category rotorcraft certificated under VFR. However, it does require placement of instruments in a logical order as close to the pilot’s central line of vision looking forward. This rule correlates with § 29.771(a) in that the placement of instruments and gauges used by the pilot to fly the rotorcraft directly affects the amount of concentration, and in some cases, fatigue. When designing a transport category VFR rotorcraft instrument panel, consider the environment in which the rotorcraft will operate. For example, at night, by definition, visibility is restricted due to darkness.
Though the meteorological definition of VMC, the pilot may or may not have a distinct horizon and could be more susceptible to spatial disorientation due to lack of visual cues. When adding instruments, not required by regulations but that the pilo t will use to operate the aircraft, ensure they are in or as close as possible to the pilot’s primary field of view. If the pilot has to spend greater time searching for information during their scan, the less time they spend looking outside for visual cues.
(1) 14 CFR 29.1321(b) defines the design requirements for the location and placement of instruments and information for rotorcraft certificated to operate IFR. .
To minimize head movement, it is important to place instruments as close to the pilot’s central line of vision as possible. This lowers the risk of pilot spatial disorientation due to vestibular stimulation or slow instrument scan due to not clustering them close to each other. The proposed types of operations and the proposed cockpit layout can provide initial information relating to pilot ability to see the instruments and gauges easily. Analysis of the angular offset of a display from the pilot’s centerline of vision may be necessary to determine how accessible that display is in a visual scan.
Currently, integrated display technology allows display of primary flight information in front of the pilot without the loss of critical flight display parameters. Additionally, the visual angle subtended by the display may be used to determine how readable the display will be (apparent display size). Final assessment of the acceptability of the visibility of the instruments will require a geometrically correct mockup or the actual rotorcraft.
(2) Figures AC 29 MG 20-1 and AC 29 MG 20-2 show the horizontal and vertical, primary and secondary fields of view for use in rotorcraft installations.
(i) Primary field of view. The primary field of view is for high priority information the pilot needs to see to operate the rotorcraft. The pilot must be able to Page MG 20 - 17
Primary LT -----,r:~15 ° ---- C/L 15 ° RT Horizontal Field Secondary LT 30° C/L AC 29-2C, Chg 7 2/4/2016 scan and access information in the primary field of view with little to no head movement.
Examples of information normally placed in the primary field of view are:
Primary Flight Information (PFI).
Master warning or caution (or high priority warnings and caution messages if not providing a master warning or caution annunciator).
Autopilot and flight guidance system modes.
Navigation information relating to course and vertical guidance and deviation.
Primary powerplant information (NR/N2, TQ, N1, TOT).
(ii) Secondary Field of View. The secondary field of view is for information the pilot needs but that is not as high a priority as primary flight information.
The pilot should be able to see information in the secondary field of view with little head movement. However, the further away from the primary field of view, the more the pilot needs to turn his head to see the instrument. Take the importance of the information the pilot is looking for into account when placing instruments and gauges within the secondary field of view. Examples of information placed in the secondary field of view are:
Crew Advisory Warning System (CAWS) panel (if a master warning caution annunciator is installed and in the pilot’s primary field of view).
Secondary power plant information.
Autopilot or Flight Director control functions.
Standby instruments.
Navigation control and selection Horizontal Fields of View Horizontal Fields of View Figure AC 29 MG 20-1. Primary and Secondary Horizontal Fields of View Page MG 20 -18
Vertical Fields of View of View Primary Secondary Horiz 0 15 _15 0 NOM NOM ON Vertical Field Figure AC 29 MG 20-2: Primary and Secondary Vertical Fields of View (B) Section 29.1321(d). This regulatory provision is also closely related to §§ 29.771(a) and 29.1322 (if the instrument has a failure light or flag). The evaluation considerations discussed under those sections are applicable here as well.
Demonstrations and tests intended to show compliance should use production quality hardware and be conducted in a variety of lighting conditions (for example, dark, bright forward field, shafting sunlight). Due to the effect other rotorcraft electrical systems have on individual systems, compliance tests should be conducted in the rotorcraft, although there may be submittal of supporting data from laboratory testing to supplement rotorcraft testing.
(ix) Section 29.1322. The regulation specifically applies to lights. However, this section of the guidance also discusses audio alerts since there is simultaneous use with visual alerts to relay information to the pilot.
(A) With the advent of the integrated electronic multifunction display (MFD) systems, many manufacturers are presenting warnings, cautions, and alerts on MFDs instead of on separate annunciation panels. Consequently, this regulation is applied routinely to these integrated electronic displays.
(1) The use of red and amber for encoding purposes other than warnings and cautions can create confusion on these displays.
(2) Use red only as a warning annunciation for emergency operational conditions when immediate flight crew recognition and action is required.
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AC 29-2C, Chg 7 2/4/2016
(3) Use amber only for cautionary alerting and when immediate crew awareness is required and subsequent action may be required. Use white or another unique color for advisory annunciations of operational conditions that require flight crew awareness but may not require any action.
(4) Use green only to indicate safe operating conditions.
(B) Applicants should describe each warning, caution, and advisory light, including the expected pilot response. Consider establishing a well-defined color coding philosophy consistently across the cockpit. A well -defined and consistent color philosophy can greatly reduce the likelihood of confusion and interpretation errors.
(C) Evaluations should be conducted in the rotorcraft using actual hardware. Testing should include a variety of lighting conditions. It is important that the selected colors maintain integrity (for example, red looks red, amber looks amber) and discriminability (that is, colors can be distinguished reliably from each other) from all potential viewing angles and under all expected lighting levels.
(D) ) CAS panels should be easily seen and labels and messages easily legible in all lighting conditions. The lighting of the panel should balance with the rest of the cockpit. Modification of CAS panels, such as filtering for NVIS lighting, should be evaluated in all lighting conditions and pilot viewing angles to ensure the CAS legends are easily seen and legible.
(E) Audio Alerts, Cautions, and Warnings:
(1) It is important to use audio alerts judiciously. Keep the number of audio alarms to the minimum necessary to provide the desired result. Too many alerts can become confusing, annoying, increase pilot workload, and detract from a pilot’s primary flight responsibilities.
(2) Spoken (voice) alerts can have advantages over other forms of audio warnings since they convey specific information without the pilot having to interpret a tone or revert to a visual display to determine the exact failure.
(3) Regardless of the method chosen to present audio alerts, evaluate them to determine that they are readily detectable, easily heard under all ambient noise conditions, and quickly and correctly interpreted.
(i) Ensure that the alerting tone or voice message is of sufficient intensity (loudness) that it clearly stands out against all normal background noise.
(ii) Audio levels should be easily set and controlled in the event one alert is overly loud and distracting (for example, an audio alert is diverted from a cockpit speaker to headsets, adjustment of the alert’s volume may be necessary to compensate for the lower ambient noise of a headset vs. the ambient noise in a cockpit.
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(x) Section 29.1357(d). Applicants may choose to use methods similar to those employed for § 29.777 to demonstrate the ability of the pilot to identify and reach a specific circuit breaker or fuse when essential to safety in flight. Applicants should describe how to evaluate the ability of the pilot to identify the device readily and whether it is installed on a circuit breaker panel or controlled using an electronic device (such as a screen that can display the circuit breaker status and is controllable). The use of a circuit breaker or fuse as a switch to power-on or power-off equipment is not an acceptable design practice since the circuit breaker or fuse are not intended to function as a switch.
(xi) Section 29.1381.
(A) This regulation directly correlates with § 29.773. The primary purpose of cockpit lighting is to allow the crew to quickly see, accurately locate, identify, and, if appropriate, interact with displays or controls under both low and high ambient lighting conditions. It is especially important to be able to easily read all of the illuminated information that appears on the warning, caution, or advisories displays. All illuminated information must be easily identifiable, readable, and controllable by the pilot under all ambient lighting environments (direct sunlight to total darkness). Cockpit lighting evaluations should ensure that:
(1) There is enough lighting to make the performance of all related tasks easy to accomplish with a high level of speed and accuracy.
(2) The pilot is able to recognize and see any hazardous condition or potential hazards quickly.
(3) There is visual comfort.
(4) The lighting does not introduce glare, reflections, or flicker.
(5) The lighting system provides the pilot with the ability to balance illumination levels across all instruments and illuminated equipment.
(B) Each lighted component should be evaluated for uniform lighting and balance both individually and with all other illuminated instruments. This includes other displays, controls, alerting systems and secondary lighting, all of which should be compatible with each other. Dimming controls should be examined for uniform operation from full bright to off. The dimming ranges should be sufficient to obtain adequate readability throughout the entire operational lighting environment. Consider the number of dimming controls in the cockpit. The more dimming controls the pilot must operate, the greater the workload and likelihood of confusion and operator error;
therefore, dimming controls should be kept to the minimum required.
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AC 29-2C, Chg 7 2/4/2016 (C) Evaluate all control markings to ensure they are visible and evenly illuminated during both night and day operations. Font size variations (i.e., character size, width, and height) of the illuminated displays can affect readability and perceived brightness. Variations in font size may create perceived lighting imbalances in the cockpit (see ARP 4103 for recommendations). Lighting of one control should not interfere with viewing and identification of adjacent controls. Also, evaluate alerting lights for adequate attention-getting value for both day and night operations.
(D) Inspection of the cockpit for glare and reflections should be part of the evaluation procedure. Evaluations should ensure that glare and reflections do not cause visual discomfort, impair viewing out of the window, or interfere with other visual tasks. Lighting tests may be conducted in a cockpit mockup or simulator, if available.
Rotorcraft ground and flight tests should be conducted for both day and night operations.
(E) Ensure that all necessary instruments and panels are easily legible in all daylight conditions. This is particularly important for CAWS panels and annunciators.
Lit indicators or panels added to the rotorcraft should be assessed for legibility in all regimes used when assessing § 29.773.
(xii) Section 29.1523. This regulation addresses the criteria for determining minimum crew through the evaluation of pilot workload. Pilot workload is affected by the kind of operation being performed. So the kinds of operations being sought in
29.1525 should be considered when developing a showing of compliance. Pilot workload should consider the effect of installed systems on the following:
(A) flight path control, (B) collision avoidance, (C) navigation, (D) communications, (E) operation and monitoring of all essential rotorcraft systems, (F) command decisions, and (G) the accessibility and ease of operation of necessary controls by the appropriate crewmember assuming:
(1) Crewmember at flight or duty station.
(2) Normal, non-normal, and emergency conditions.
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(xiii) Section 29.1525. This regulation does not differentiate between the types of activities and areas that must be considered for the different kinds of operations for which the rotorcraft is approved. A source to assist with workload areas is Appendix D to part 25, coupled with the kinds of operations sought in accordance with § 29.1525.
In many cases, the minimum crew size is set by design, before any pilot workload evaluations are conducted.. This is a common practice, as the rotorcraft performance characteristics and cockpit configuration may resemble other FAA certificated models produced by the manufacturer.
(A) The process and level of evaluation for determining minimum crew for these situations will depend on the differences between already certificated models and configurations, and the model or configuration seeking certification. There needs to be a much more thorough evaluation for a new model than for a follow-on model or a model with minor modifications to the cockpit. Regardless of the level of difference or modification, evaluate all new or modified systems or new procedures for impact on the proposed minimum crew and the pilot or system interface. For rotorcraft with an established minimum crew, the purpose of this testing will be to corroborate by demonstration the predicted crew workload submitted by applicants in order to substantiate compliance with § 29.1523. Testing is also to provide an independent and comprehensive assessment of individual crewmember workload in a realistic operating environment. Any problems or issues identified with the system would most likely be resolved through design or procedural changes.
(B) Supplemental type certificate or amended type certificate modifications to avionics systems can significantly alter pilot workload, particularly if the modification adds new digital or electronic display and flight guidance technology into an older, mostly “round-dial” or analog cockpit. Avionics modernization modifications normally change pilot interaction with the rotorcraft. Integration of modern systems with existing systems can create unintended workload changes that create issues with the pilot’s primary function of flying the rotorcraft. For example, the performance capabilities of an older autopilot can hamper the new capabilities of a more modern GPS installed in a rotorcraft. Enabling the new capabilities by relying on the pilot to compensate for the inadequate performance of the integration is not recommended and may raise issues regarding the original minimum crew determination.
(C) Assessment of pilot workload is critical in evaluating the effectiveness of the integration of new technology with old. Net pilot workload may not increase or decrease, but it may change from simple aviation to one of systems management. The type of workload change should be assessed to evaluate the integration of systems.
Designs that incorporate special “pilot work-arounds” to account for incompatibilities between the new system and the existing systems may raise certification issues. These “pilot work-arounds” can create issues for operators trying to exploit the new capabilities of the system because they may not meet requirements in part 91 or part 135. Any time a design requires the pilot to compensate or change the way he operates in the cockpit to account for an integration issue, it should be questioned and corrected.
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AC 29-2C, Chg 7 2/4/2016 (D) Assess the workload through a logical process of analysis, measurement and demonstration. One acceptable analytical approach would assess workload as a percentage of time available to perform tasks (time-line analysis). Use an evaluation that collects objective and subjective data from subject pilots. The FAA and U.S Air Force developed a report for certification use to assist in evaluation of pilot workload. This report, “Assessment of Crew Workload Measurement Methods, Techniques, and Procedures,” Volume II (Report No. WRDC-TR-89-7006), provides guidance for selecting and using a number of subjective, physiological, and performance based workload measurement techniques.
(E) Depending on the level of integration required, use of a buildup approach may be helpful. Use of integrated bench tests, ground mock-ups, and if possible ground tests with an installed system helps identify issues early. Use of video and audio recordings can assist in analyzing pilot interactions with systems in all phases of testing including flight tests. Test flights should assess workload in all expected environments and for all operations requested in accordance with § 29.1525, part 91, and part 135.
(F An evaluation team is usually assembled when certificated systems and the proposed system are significantly different. Such a team includes applicant test pilots, certification authority test pilots, and, if the certification team deems it advisable, “line pilots” who routinely fly similar rotorcraft. The testing should be conducted using scenarios representative of the type of operations used for the rotorcraft. Testing should include various types of routes, navigational aids, environmental conditions and traffic densities. Give particular attention to tasks that involve planning and execution of emergency and non-normal procedures. When appropriate, also consider dispatch under the Master Minimum Equipment List in combination with other failures that are likely to result in significantly increased pilot and crew workload. Since display format and media also influence workload, the number, size, location, type of display, and presentation format should also be part of the overall evaluation.
(G) Discussion of minimum crew and the associated crew workload between the involved certification authorities and the applicant should take place early in the development cycle. These discussions should focus on identification of design features that are likely to affect crew workload. These design features need to be evaluated to ensure that they do not place excessive workload demands on any crewmember. Applicants should submit a test plan describing the details of the evaluation approach. Although developed for transport category airplanes, AC 25.1523 also contains useful information to address this rule.
(xiv) Section 29.1555(a). The intent of this regulatory provision is to ensure that pilots can quickly and unambiguously identify the function and understand the method of operation for each cockpit control. In conventional designs, the marking or labeling of controls may be accomplished using text that describes the function of that control. With the advent of MFDs and integrated systems, there is an emerging trend to integrate control functions into these displays. Many traditional systems (e.g., fuel, Page MG 20 -24