Flight test certification of multipurpose head-up display for general aviation aircraft

Abstract

Advances in flight display technology have enabled manufacturers to provide a head-up display (HUD) of aircraft control and performance parameters for use in general aviation aircraft without the use of inertial platforms or specialized data bus architecture. The Federal Aviation Administration currently has no regulatory guidance regarding HUD or flight symbology certification. A specific certification pro- gram is presented. The process of categorizing the HUD as a supplemental system instead of a primary display is discussed. Flight display symbology is discussed, and the final symbology set is presented. The certification flight test plan is discussed including the requirements for functional, usability, and opera- tional testing. Flight test data are discussed. A HUD system was certified for single-pilot use in instrument meteorological conditions in a general aviation aircraft. HE head-up-displ ay (HUD) was first developed in mili- tary aircraft from reflecting optical sights. The HUD places flight and navigation data in the pilot's forward field of view (FOV). These data are presented through various symbols as a collimated image that appears to be floating at infinity. Early HUDs were used for weapons delivery with displays tailored for a single task. HUDs today can provide a variety of aircraft state and navigation data. Recent HUD develop- ment, as an enhancement tool to facilitate manually flown in- strument approaches to weather minima as low as a runway visual range of 1200 ft, has obvious implications for air carrier operations. The ability to ease the instrument-to-visual ap- proach transition and acquire the runway environment sooner is a desirable feature of any cockpit display system. Though these systems usually require high-fidelity inertial reference platforms and are costly, the advantage gained in arrival reli- ability has been deemed cost effective. Additionally, because the pilot has state and navigation data available while looking through the aircraft windscreen, the increased ability to visu- ally clear for other traffic is a safety enhancement. Current HUD development and operational concept are toward dis- plays that are useful and certifiable during all phases of flight. Lower cost displays that do not provide enhanced capability, but do provide increased out-of-the-cockpit awareness for cor- porate and general aviation aircraft are also emerging into the marketplace. A typical HUD displays airspeed, altitude, pitch and roll attitude, and heading. In addition, navigation or mission data can usually be selected for display. Flight director modes, radar altitude, and marker beacon passage can also be shown, if available. Most HUDs can also display master warning and caution annunciators. The subject HUD was targeted for the corporate and general aviation industry. This HUD differed from other operational systems in that it used conventional aircraft gyros and did not depend on an inertial navigation system platform for attitude information. Since conventional aircraft gyros are less precise than inertial platforms, the HUD symbology was not confor-