SAE ARP4822A

This SAE Aerospace Recommended Practice (ARP) reviews the basics of NVIS compatibility and discusses the specific illuminated pushbutton switch and indicator requirements for sunlight readability, color, luminance, and NVIS radiance when used in NVIS compatible cockpits. The recommendations and special considerations set forth in this document are made to give the design engineer a better understanding of MIL-L-85762A and MIL-STD-3009 NVIS compatibility requirements and to provide information on the visual characteristics of NVIS compatible pushbutton switch and indicators. The recommendations are primarly for military aircraft since civilian aircraft FAR requirements typically do not cover NVIS applications with the exception of those covered by RTCA/DO-275. Warning, caution and advisory push-button switches and indicators are considered by pilots to be one of the most important items in the aircraft crew station. With well defined and historical application of aviation color requirements, these push-button switches and indicators can be particularly difficult to achieve in an NVG green-lighted compatible crew station with chromaticity limits now defined by military specifications that are lacking in most FAR documents. This specific technology, which is utilized to deal with the design of these devices is covered in this document. The most recent revision to is update the references, add Class C response curve and to correct some photometric and radiometric requirements.