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AFRL - Automatic Collision Avoidance Technology (ACAT)

The Automatic Collision Avoidance Technology Fighter Risk Reduction Programs were established to develop an automatic solution to protect fighter pilots from Controlled Flight into Terrain (CFIT) mishaps and mid-air collisions.

The Automatic Ground Collision Avoidance System (Auto GCAS) is an on-board system that prevents an aircraft from impacting the ground by automatically pulling the aircraft up before an accident can occur. Auto GCAS has been flight tested and integrated on the USAF Block 40/50 F-16s.  

Seventy-five percent of F-16 fatalities are due to CFIT, spatial disorientation, and g loss of consciousness: our Automatic Ground Collision Avoidance System (Auto GCAS) can prevent 98 percent of these.  Since September 2014, Auto GCAS is credited with saving 7 aircraft and 8 pilots.

Approximately 25 percent of U.S. F-16 operations-related mishaps are due to aerial collisions and the Automatic Air Collision Avoidance System (Auto ACAS) has been designed to prevent the majority of these mishaps, using data links as the primary method to share information necessary to predict and avoid collisions. In addition, radar track information can be used to predict collisions. Auto ACAS protects aircraft from colliding by maneuvering the aircraft at the last possible instant before an accident can occur.

Both an Automatic Ground Collision Avoidance System (Auto GCAS) and an Automatic Air Collision Avoidance System (Auto ACAS) are needed to protect fighter pilots from Controlled Flight into Terrain (CFIT) accidents and mid-air collisions. The challenges include making sure the systems do not harm the aircraft (i.e. over g the aircraft) and ensuring they do not impede the pilot’s mission (i.e. they don't cause nuisances) while providing protection to the pilot from ground and mid-air collisions. The Automatic Integrated Collision Avoidance System is needed to integrate Auto GCAS and Auto ACAS into one system, thus making the systems compatible with one another.

Auto GCAS  for aircraft with digital flight control computers was integrated on the USAF block 40/50 F-16s in Fall 2014. Auto GCAS will look to future platforms for implementation.  Analog Auto GCAS/Hybrid-Technology has been tested out on an older F-16 equipped with an analog flight control computer.  These older F-16s, known as pre-block 40s, make up about one third of the US Air Force F-16 fleet. This version of Auto GCAS was first flight tested in 2016, and will undergo a final test program in 2018 before being certified as ready to fly on the pre-block 40 F-16 fleet.  

AFRL's Auto ACAS effort was completed in 2014. Auto ACAS was then combined with Auto GCAS under the Auto ICAS phase of the program, thus allowing this system to be transitioned and fielded under Auto ICAS. Any issues found with Auto ACAS were addressed in AFRL's Auto ICAS program. 

The Auto ICAS flight test program ended in October 2017. The test team is analyzing all the flight data and will make a formal recommendation regarding Auto ICAS’s readiness to transition out of AFRL and into a fighter fleet.

AFRL is investigating the feasibility of applying the Auto GCAS technology to cargo aircraft such as the C-130. Adapting Auto GCAS to these aircraft is a different challenge than the one previously solved for fighter aircraft, because cargo aircraft cannot simply climb over all nearby terrain. Solutions are being investigated and flight tested in cooperation between AFRL, the Air Force Institute of Technology, and the Air Force Test Pilot School.