·        Documentation should include the results of analyses and tests that show that any delayed or inhibited alerts do not adversely impact safety. [AC 25.1322-1, 8.a(5)]

·        When following the guidance in AC 25.1322-1, document any divergence, and provide the rationale for decisions regarding novel or unusual features used in the design of the alerting system. This will facilitate the certification evaluation because it will enable the FAA to focus on areas where the proposed system diverges from the AC and has new or novel features. [AC 25.1322-1, 13.b]

·        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 aircraft electrical systems have on individual systems, compliance tests should be conducted in the airplane, although supporting data from laboratory testing may be submitted to supplement airplane testing. [PS-ACE100-2001-004, Appendix A]

·        We recommend developing a plan to establish how compliance with the rules will be shown and to document how issues will be identified, tracked, and resolved throughout the life cycle of the certification program. We also recommend including the FAA early in the developmental process to discuss the acceptability of any proposed flight-deck-design-and-alerting philosophy and the conditions that should be alerted to the flightcrew. Typically, a certification plan is used for this purpose. [AC 25.1322-1, 13.a]

·        In accordance with the certification plan, provide an evaluation of the alerting system. In this case an evaluation is an assessment of the alerting system conducted by an applicant, who then provides a report of the results to the FAA. Evaluations are different from tests because the representation of the alerting system does not necessarily conform to the final documentation and the FAA may or may not be present. Evaluations by the applicant may contribute to a finding of compliance, but they do not constitute a complete showing of compliance by themselves. [AC 25.1322-1, 13.c]

        (1)   The evaluation should include assessments of acceptable performance of the intended functions, including the human-machine interface, and acceptability of alerting system failure scenarios. The scenarios should reflect the expected operational use of the system. Specific aspects that should be included during the evaluation(s) are:

                (a)   Visual, aural, and tactile/haptic aspects of the alert(s).

                (b)   Effectiveness of meeting intended function from the human/machine integration, including workload, the potential for flightcrew errors, and confusion.

                (c)   Normal and emergency inhibition-and-suppression logic and accessibility of related controls.

                (d)   Proper integration with other systems, including labeling. This may require testing each particular alert and verifying that the appropriate procedures are provided.

                (e)   Acceptability of operation during failure modes per § 25.1309.

                (f)    Compatibility with other displays and controls, including multiple warnings.

                (g)   Ensuring that the alerting system by itself does not issue nuisance alerts or interfere with other systems.

                (h)   Inhibiting alerts for specific phases of flight (for example, takeoff and landing) and for specific airplane configurations (for example, abnormal flaps and gear).

        (2)   The validation of the performance and integrity aspects will typically be accomplished by a combination of the following methods:

                -       Analysis

                -       Laboratory test

                -       Simulation

                -       Flight test

        (3)   Evaluate the alerts in isolation and combination throughout the appropriate phases of flight and maneuvers, as well as representative environmental and operational conditions. The alerting function as a whole needs to be evaluated in a representative flight deck environment. Representative simulators can be used to accomplish the evaluation of some human factors and workload studies. The level and fidelity of the simulator should be commensurate with the certification credit being sought. The simulator should represent the flight deck configuration and be validated by the FAA. The assessment of the alerts may be conducted in a laboratory, simulator, or the actual airplane. Certain elements of the alerting system may have to be validated in the actual airplane. The evaluation should be conducted by a representative population of pilots with various backgrounds and expertise.

        (4)   Evaluations should also verify the chromaticity (red looks red and amber looks amber) and discriminability (colors can be distinguished from each other) of the colors being used, under the expected lighting levels. Evaluations may also be useful to verify the discriminability of graphic coding used on monochromatic displays. These evaluations can be affected by the specific display technology being used, so a final evaluation with production representative hardware is sometimes needed.

        See also: Chapter 8 Intended Function

·        If possible, incorporate the new tactile alert into the existing aural alerting system. If this is not possible, a separate tactile alerting system may be installed, provided that the following elements are included: A means to ensure that an individual alert can be understood and acted upon. This may require a demonstration of any likely combination of simultaneous alerts. [AC 25.1322-1, 14.d(2)(b)]