Auto GCAS for analog flight control system

Over the past forty years, the number of fighter aircraft controlled flight into terrain (CFIT) accidents per flight hour has not improved despite the addition of multiple manual warning systems. The Air Force Research Laboratory (AFRL) has undertaken a program to develop an automatic system that will take over when the pilot can no longer recover the aircraft, perform an automatic recovery and quickly return control to the pilot. It is called the Automatic Ground Collision Avoidance System or Auto GCAS. This system has been successfully demonstrated on a Block 50 F-16 with a digital flight control system as shown in Figure 1 and is transitioning to operational Block 40/50 F-16s. Until now the technology could not be applied to early model F-16s with analog flight control systems because of the lack of a high authority autopilot needed for the automatic recovery and the absence of a way for the flight control system to ascertain system integrity to insure safe operation. AFRL is now focused on finding a technical solution that will allow the implementation of Auto GCAS on aircraft with analog flight control systems. The effort is called Analog Auto GCAS. The Analog Auto GCAS project has developed an innovative method of adding redundant digital processor modules to the existing analog flight control computers of pre-block 40 F-16's. This will not only allow Auto GCAS to be added to F-16s with analog flight control computer but demonstrates a technical path forward for incorporating Auto GCAS onto other older aircraft with analog flight control computers. This paper provides a description of Auto GCAS, discusses the changes needed to implement Auto GCAS on an analog aircraft, and covers the results to date as well as the future path forward for implementing Auto GCAS on the pre-block 40 F-16 fleet.