AWO.A.HUD.110 CS AWO.A.HUD.110 Head-up displays used for enhanced flight vision systems

- (a) HUDs (or equivalent displays) used to display enhanced flight vision system (EFVS) imagery shall have a field of regard (FOR) that is appropriate to the intended usage (see CS AWO.A.EFVS.104(b), (c) and (d)). - (b) Where the EFVS image is superimposed on the HUD (or equivalent display) symbology, then the EFVS image and installation shall, in the absence of any failure: - (1) satisfactorily perform its intended function; - (2) permit the accurate identification and utilisation of visual references, using both EFVS and natural vision, as appropriate; - (3) have acceptable display characteristics to accomplish the intended function; - (4) not degrade the presentation of essential flight information listed in CS AWO.A.EFVS.105(a) on the HUD (or equivalent display); - (5) not be misleading and not cause confusion nor any significant increase in pilot workload;

- (6) be aligned with and scaled to the external scene, and consider, if needed, the effect of parallax; - (7) not alter the colour perception of the external scene in ways that cause confusion, significantly increase pilot workload, or prevent the pilot from performing any required tasks (e.g. discerning precision approach path indicators (PAPIs)); - (8) permit the pilot to recognise misaligned or non-conformal conditions to the external scene that may preclude the pilot's performance of any required manoeuvres;

Note: The misalignment or non-conformal conditions shall be those that can be detected by the system.

- (9) provide a means to control the EFVS scene brightness that is independent of the HUD (or equivalent display) symbology brightness control; this control shall be operable without causing excessive pilot workload, and not cause adverse physiological effects such as fatigue or eye strain; - (10) provide a readily accessible control to enable the pilot to remove and reactivate the EFVS image from the HUD (or equivalent display) without requiring the pilot to remove their hands from the primary flight controls and thrust control.

[Issue: CS-AWO/2]