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New aircraft are being developed incorporating head—up displays (HUD5 ) to serve as primary flight references (PFRs) in all phases of flight. HUDs have been used in military airplanes as weapon displays and as primary flight references. They have been approved in some civil aircraft as part—time displays for approach and landing or as supplementary displays. The HUD offers several advantages over conventional instruments: Reduced pilot workload; Increased flight precision; Direct visualization of trajectory; and Less eyes—inside—the—cockpit. At the same time, these advan— tages can sometimes create problems (I. e • , There is no free lunch) . Two instances are clutter and rapid display motion In spite of these difficulties, the use of a HUD can be an overall unproveinent in flight instrumentation, provided that attention is paid to the problem areas. A design guide is available)HUDs have been certificated on civil aircraft since the early 1970s. They have usually been restricted to specific flight phases (approach and landing). All have supplemented head down instruments, not replaced them. A Flight Dynamics HUD is being developed for the Lockheed C-130J for use as the primary flight reference (a stand-alone PFR). There is interest in the airline community for enhanced vision systems (EVS) or synthetic vision systems (SVS). As envisioned by proponents, EVS/SVS would use a raster-capable HUD which would show electronic imagery from some kind of sensor. Both millimeter wave radar and FLIR have been proposed. The operational scenario would use the electronic image in place of direct view of the runway environment. The pilot would base descent below instrument minimums on the view of the sensor image of the runway. A certification project is underway for an enhanced vision system to be installed on B—747 airplanes. Helicopter operators would like to use night vision technology, based on image intensifier night-vision goggles or on infrared head—mounted displays (HMD5). Such displays have been suggested to aid emergency medical service flights to accident sites. Several helicopter ambulance operators have requested operational approval for night—vision goggles.
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