(i) Drawings of the cockpit layout showing positions of system components, even if preliminary, are beneficial for providing an understanding of the intended overall cockpit arrangement (controls, displays, sample display screens, seating, stowage, and so forth). Including measurements and dimensions of displays, their locations and locations of controls relative to the pilot's central line of vision or the design eye position is also beneficial to both the applicant's and certification authority teams.
As the system design changes, keep the certification team updated so they are current on proposed changes. Give special attention to the following, especially if they are novel or unique:
(A) Arrangements of the controls, displays, or other cockpit or flight deck features or equipment.
(B) Controls, such as cursor control devices, touchscreen displays, or new applications of existing control technology.
(C) Content, format, and function of the pilot interface on the display as generated by the systems software.
(D) Display hardware technology.
(E) Screen usage, alerting mechanisms, and mode annunciation.
(ii) Sketches of the crew interfaces for the specific systems or the items listed above can be helpful in providing an early understanding of the features that may face certification issues.
(4) Underlying principles for automation logic (§ 27.1309, § 27.1329, and Appendix B to part 21).
Define the system's automated functions design early in the process. The automation features should follow a design philosophy that supports the intended functions regarding the system behavior, modes of operation, and pilot interface with controls, displays, and alerts. For designs that involve significant automation, the way automation operates and communicates that operation to the pilot can have significant effects on the crew interface. The system description should include, but not be limited to:
(i) Pilot actions to engage or disengage, or activate or deactivate, modes and features.
(ii) Principles underlying mode transition.
(iii) Mode annunciation scheme.
(iv) Automation engagement or disengagement principles.
(v) Level of automation.
(vi) Logic diagrams and complexity of the logic, if available.
(vii) Failure modes, how they appear to the pilot, and how the pilot's interaction with the system and rotorcraft changes.
(5) Operational considerations (§ 27.1523, Minimum flight crew; § 27.1525, Kinds of operations).
Consider consulting the AEG inspector that is responsible for the make and model of rotorcraft on the system installation.
(1) Pilot characteristics (§ 27.1523). The FAA has not accepted certain designs, in past projects, that specifically relied on crew resource management or certain pilot characteristics to mitigate a system design flaw. Consider assessing the level of certification, skill, and knowledge a "nominal pilot" possesses in order to evaluate the pilot workload when interacting with the system and rotorcraft.
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AC 27-1B, Chg 7 2/4/2016
(ii) Identify the operations the system is designed to support. Although sometimes considered less complex than installations for operation under IFR, the HF evaluation of installations for operation under VFR should include the same rigor, as both present HF challenges to the pilot. For example, complex systems or systems that require the pilot to spend considerable time interfacing with a system's functions and interactions with other rotorcraft systems will require the pilot to allocate attention from flying the rotorcraft. The results are increased workload with varying changes in the pilot's ability to attend to flying the rotorcraft. The following are some considerations:
(A) For rotorcraft operating only under VFR, describe the operations the system is meant to support, taking into account day and night operations. For example, for installation of an electronic display systems (EDS) display suite that integrates with external GPS navigators, consider:
(1) The effect of the pilot-system interface on the pilot's attention allocation and workload.
(2) How it affects the pilot's external scan and "see and avoid" tasks (whether it requires extensive heads-down time).
(B) For rotorcraft certificated to operate under IFR, describe the operations the system supports. For example, for installation of a new EDS suite and a WAAS GPS system that interfaces with the existing autopilot and one of the new operations is steep angle low speed approaches, consider how the system will support or change pilot workload.
(iii) System Operation procedures. Describe and evaluate the pilot procedures for both normal and abnormal conditions since the design of the system and use of procedures are interrelated.
Additionally, development and presentation of procedures and limitations can affect pilot workload, particularly in abnormal conditions. Identify and evaluate any expected pilot memory or "bold-face" items (procedures that the pilot must perform from memory prior to referencing a checklist or flight manual). In addition to the flight manual or flight manual supplement, system operations procedures may include:
(A) Quick reference handbook to accompany the flight manual.
(B) Abbreviated checklists to accompany the flight manual.
e. Certification Requirements. Identify the regulations in the certification basis for system or component installations that have HF implications. These can be identified either as part of the certification plan or a separate human factors certification plan. The certification plan should indicate the method of compliance for each regulation and contain sufficient detail to ensure human factors considerations are adequately addressed. The plan should also allow adequate time to accomplish all necessary testing agreed to by the applicant and the FAA.
(1) Address and evaluate the following in the certification plan:
(i) The intended use of the system does not require any exceptional skill or generate any unreasonable workload for the pilot.
(Il) The use of the display does not require unreasonable training requirements to demonstrate adequately that the pilot can understand and properly operate the system in all operational environments.
(ili) Demonstration of the design characteristics of the display system support error avoidance and management (e.g., detection, recovery, etc.).
(iv) The display system integration is consistent or compatible with other cockpit controls and creates no added burden on the pilot with respect to the new display system or operation of other Page MG 20 -8
(v) If a failure occurs, it will not prevent the pilot from safely operating the rotorcraft.
(2) The manufacturers should provide design rationale for their decisions regarding new or unique features in a display. Evaluation pilots should verify that the data support a conclusion that any new or unique features have no unsafe or misleading design characteristics.
(3) Several pilots as well as human factors representatives should conduct display and system interface evaluations particularly when the applicant is installing a system for the first time in a particular category of helicopter. More than one test pilot should be used to ensure multiple data inputs. For systems that contain new or unique features, consider a greater number of evaluators. A reasonable amount of training time should be allowed to learn all required features of the display system. The evaluators should be familiar with the guidance contained in this advisory circular before performing the evaluation. Additional information helpful in developing evaluation plans. For instance, example information regarding evaluation plan development can be found in GAMA Publication No. 10, Recommended Practices and Guidelines for Part 23 Cockpit/Flight Deck Design; DOT/FAA/AM-01/17, Human Factors Design Guidelines for Multifunction Displays; and section AC 27 MG 19 of this AC.
f. Methods of Compliance. The parts of the certification plan that address the HF portions of the regulations should describe the methods used to demonstrate compliance with sufficient detail to allow the certification authority to evaluate the appropriateness and adequacy of the proposed methods of compliance. It is important that the proposed methods of HF compliance are coordinated and discussed with the certification authority to identify HF issues early in the program to avoid certification schedule delays. Paragraph h. of this MG below, contains a sample compliance matrix for HF.
g. Discussion of selected part 27 regulations related to human factors and performance.
(1) For the purposes of brevity, the regulations discussed are not restated. For all compliancerelated documents, the certification plan should use the exact wording of the regulation.
(i) This part of the guidance does not include all regulations associated with HF and flightcrew interfaces listed in the table in paragraph b. above. In addition, several of the regulations are written in general terms. In these cases, subjective data are often used to establish compliance
(il) Due to the subjective nature of many of the HF aspects of the regulations, the certification authorities encourage applicants to carefully consider and thoroughly describe the means they intend to use to demonstrate compliance with each regulation. The applicant may choose to provide the detailed description of the means of compliance in subsequent submitted test plans. Use the information contained in the discussion for each regulation, presented paragraph g. (2), to assess the appropriateness and adequacy of the chosen methods. The certification authority and the applicant should meet to discuss and reach agreement as to the acceptability of the proposed techniques prior to the collection of compliance demonstration data. Demonstrate compliance through similarity and minimal testing for simple and straightforward applications that have little impact on pilot workload, system awareness, tasking, or performance. It should be understood that the regulations discussed in paragraph g. (2) are (Ili) More complex, integrated designs may require pilot evaluation under actual anticipated flight conditions after the performance of analytical and component-level bench evaluations. For these tests, it is critical the flight test pilots are objective regarding their performance using systems and controls. If using pilots other than test pilots, observers should be alert to possible differences between how the pilot performs and interfaces with a system and the pilot's ratings. The test program should include sufficient simulation and flight testing to ensure:
(A) Reasonable training times and learning curves.
(B) Acceptable interpretation and operation error rates equivalent to or less than previously certificated comparable systems.
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AC 27-1B, Chg 7 2/4/2016 (C) The intended user (pilot) of the system does not require any exceptional skill, strength, or alertness to operate the system.
(D) Proper integration and compatibility with other controls or displays, or both, and with other equipment in the cockpit.
(iv) Typically, rotorcraft systems are designed to minimize failures. However, if a system failure occurs, the pilot should be able to continue safe operation of the rotorcraft. Pay particular attention to the hazards of presenting misleading information to the pilot in the event of malfunction. Applicants are encouraged to conduct early analyses and evaluations of new systems to facilitate timely identification and resolution of HF related certification issues.
(2) The following is a partial listing of the HF-related regulations and associated discussion of each of those regulations with considerations for demonstration of compliance.
(i) Section 27.672.
(A) Section 27.672(a). Provide a warning signal that is distinguishable from other cockpit alerts. If an audio signal is used, the pilot must be able to discriminate it from all other cockpit audio alerts.
(1) Conduct evaluations in the rotorcraft during both ground and flight operations with varying levels of background noise.
(2) Assess the discriminability of the visual and auditory alert in multiple alert scenarios, if applicable.
3) Applications that employ voice technology should meet these same criteria.
(4) Conduct analysis, simulation, or flight test to show that the system would not produce nuisance alerts when the rotorcraft is conducting normal flight operations.
(B) Section 27.672(b). Determination of exceptional pilot skill or strength is subjective.
When evaluating for "exceptional pilot skill," evaluators should consider the complexity of the task in terms of the performance requirement (level of accuracy or precision), the number of steps, memory load, checklist use, time-to-perform, and, if needed, training requirements. The test pilots involved in the program normally do these evaluations. For "exceptional pilot strength," it is also important to conduct evaluations considering the minimum strength capabilities of the pilot. Consider using pilots that represent a fifth percentile female as the low-end of the strength spectrum.
(1) There is guidance that may be useful to applicants in determining strength considerations in section 27.143 of this AC and the strength study in Human Force Exertions in Aircraft Control Locations, report no. AMRL-TR-71-119, February 1972. This study provides several examples of maximum force exertion from various locations of controls in the cockpit; however, there are always unique situations that can arise during the design of a new or modified cockpit.
(2) When new or unique situations arise, conduct evaluations early on to ensure that the strength required to activate the control does not fall outside the limitations of the pilot population.
(ii) Section 27.679. A number of accidents have occurred because pilots have tried to take off with either the manufacturer's control lock or a substitute device in place. A couple of issues can cause this problem. One is whether the "unmistakable warning to the pilot" is, in fact, unmistakable.
Another is the use of unapproved devices to lock the control system. Various approaches and devices have been developed to make it apparent that the control is locked. When evaluating a control lock system, consider several factors in finding compliance with the regulation.
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(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 27.771. 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 flightcrew. 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.
(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 (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.
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AC 27-1B, Chg 7 2/4/2016 (E) Cockpit environmental control. Consider sufficient heating and cooling ability along with adequate ability to defrost or defog windscreens.
(iv) Section 27.773(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, see section 27.773 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 27.773 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. Refer to section 27.773 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 crosscockpit. 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 27.777.
(A) Section 27.777(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 identity the control easily, the ease and convenience of operation of the control, contusion 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 § 27.1555. The suggested analyses and evaluation procedures described for showing compliance with § 27.671 are also applicable and recommended for this regulation.
(B) Section 27.777(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 § 27.785(c) if Page MG 20 - 12
the pilot is strapped into the seat wearing the lap belt and shoulder harness. See also the guidance in section 27.777, paragraph b, of this AC. It is important to conduct evaluations using individuals representing a range of 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
(vi) Section 27.785. This regulation is related to § 27.777(b). Section 27.785(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 § 27.777(b) in paragraph g.(2)(v)(B) above 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 § 27.777(b), consider using individuals from a fifth percentile female and a 95th percentile male body size to assess compliance.
(vii) Section 27.1301. 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 authority 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 27.1301(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 (B) Section 27.1301(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 § 27.1555.
(vili) Section 27.1321.
(A) Section 27.1321(a). This regulatory provision does not specify the precise location in the instrument panel of flight, navigation, and powerplant instruments in normal category rotorcraft certificated under VFR. However, this rule correlates with the requirements of § 27.771(a). Placement of instruments and gauges used by the pilot to fly the rotorcraft directly affects the pilots' concentration and, in some cases, fatigue. When designing an instrument panel for normal category rotorcraft operating under VFR conditions, consider the environment in which the rotorcraft will operate. For example, at Page MG 20 - 13
AC 27-1B, Chg 7 2/4/2016 night, by definition, visibility is restricted due to darkness. Though meeting 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 which the pilot will use to operate the aircraft, ensure the instruments are in or as close as possible to the pilots' primary field of view. This will make the pilot's scan easier and less time consuming: if pilots have to spend greater time searching for information during their scan, they spend less time looking outside for visual cues.
(1) Appendix B of this AC provides design guidance for the placement instruments and information for normal category rotorcraft certificated for IFR flight. 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 27 MG 20-1 and AC 27 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 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).
(I 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.
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Horizontal Fields of View LT Secondary Primary LT 30° 15 C/L C/L 15 30° RT Horizontal Field → RT Figure AC 27 MG 20-1. Primary and Secondary Horizontal Fields of View Page MG 20 - 15
AC 27-1B, Chg 7 2/4/2016 Vertical Fields of View UP Primary Secondary 40 UP Horiz Horiz +15 ° 15° NOM 20 • -15 NOM DN Vertical Field of View Figure AC 27 MG 20-2: Primary and Secondary Vertical Fields of View (B) Section 27.1321(d). This regulatory provision is also closely related to §§ 27.771(a) and 27.1322 (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 27.1322. 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.
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 Page MG 20 - 16
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 distinguisned 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, if 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
(x) Section 27.1357(d). Applicants may choose to use methods similar to those employed for § 27.777 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 27.1367. This regulation has some similarities to § 27.777 (a) and (b), except it applies to electrical switches instead of cockpit controls. The discussion and methods of compliance discussed under that section are applicable to this one. Criticality of use should determine the location of cockpit switches (e.g., importance, frequency of use). Evaluations should be conducted with a number of pilots representing a male and female fifth percentile and 95 percentile in body size and reach. The range in size and reach are important to ensure that the location allows both extremes of pilot to see and read the label, reach the switch, and manipulate it.
(xii) Section 27.1381.
(A) This regulation directly correlates with § 27.773. 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 Page MG 20 - 17
AC 27-1B, Chg 7 2/4/2016 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.
(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 § 27.773.
(xiii) Section 27.1523. This regulation addresses the criteria for determining minimum crew through the evaluation of individual workload. Pilot workload is affected by the kind of operation being performed. Therefore, the regulation requires that the kinds of operations authorized under section
27.1525 be considered when developing a showing of compliance under section 27.1523. Additionally, pilot workload should consider the effect of installed systems on the following:
(A) flight path control, (B) collision avoidance, (C) navigation, Page MG 20 -18