Ground Collision Avoidance Technology (GCAT)
On a recent flight in a Block 40 F-16 with our squadron’s weapons officer I was introduced to the new pilot-activated recovery system (PARS). Starting at about 20,000 feet (FL 200) we rolled inverted and started a rapid 30 degree nose-low dive. The pilot pressed a button initiating the PARS. Immediately the aircraft’s computer took command of the flight controls and we experienced a very intense 180-degree roll until wings level followed by a 5-G pull-up at 4 G’s/second until we were again flying straight and level. On the second demonstration we put the aircraft in a 30-40 degree nose-up attitude. After PARS initiation, the Viper went into autopilot controlling the roll and yaw of the aircraft while allowing the nose to slice down until we were again straight and level.
This PARS feature is part of the F-16’s newest upgrade to avoid mishaps due to controlled flight into terrain (CFIT). The entire fleet of F-16’s in the USAF received this important upgrade during the 2014 calendar year. This is incredibly EXCITING news for the fighter pilot community and hopefully will translate into hundreds of lives and billions of dollars saved. CFIT occurs for a variety of reasons and plagues aviation taking the lives of hundreds of military and general aviation pilots each year. Aside from PARS, the other application of this new capability is the Auto-GCAS (Ground Collision Avoidance System). Auto-GCAS provokes inputs to the flight controls similar to the PARS feature described above, but happens automatically without pilot initiation. The technology relies on sophisticated computer software, terrain maps, GPS and predictive algorithms that will ‘take the jet’ from the pilot when CFIT is predicted to be imminent.
A video HUD demo of the Auto-GCAS can be seen directly below, and further below a NASA video discussing how the GCAT technology was developed and works.
A Brief History of GCAT
The GCAT software was developed by NASA’s Armstrong Flight Research Center at Edwards AFB, in partnership with the Office of the Undersecretary for Personnel and Readiness, the Air Force Research Laboratory (AFRL), the Air Force Test Center (AFTC) and Lockheed Martin. The technology began development in the 1980’s and was ready for testing by the late 1990’s. By 2009, the Ground Collision Avoidance Technology was incorporated into an upgraded USAF Block 25 F-16D and underwent further testing at Edwards AFB, CA.
According to NASA: “The team conducted more than 556 test maneuvers during 49 flights, some of which involved diving at the ground and toward the sides of mountains. Key objectives included demonstrating that Auto-GCAS could significantly reduce the number of mishaps resulting from pilot spatial disorientation, loss of situational awareness, gravity-induced loss of consciousness, and landing-gear-up landings.”
Air Force officials announced in 2013 that an operational Auto-GCAS system would be installed in the F-16 fleet and this largely took place throughout the 2014 calendar year. At the base I am currently stationed, we received the upgrade in Sep-Oct 2014. The application has also been tested for general aviation. In 2012, Auto-GCAS was adapted for a small, unmanned research aircraft and implemented as a smartphone application using the Android operating system linked to the aircraft’s autopilot. There remain plans to develop similar systems that can be incorporated into the F-22, F-35, and F-18.
Strengths & Limitations of GCAT
Two of the most common human factors conditions that lead to death or loss of aircraft in combat aviation are spatial disorientation and G-induced loss of consciousness (G-LOC). Spatial Disorientation is the inability to determine one’s position, location, and motion relative to their environment, and is covered in greater detail in a separate post. There are three types of Spatial D: Unrecognized, Recognized, and Incapacitating. The Pilot-Activated Recovery System (PARS) will save pilots suffering from recognized and capacitating Spatial-D as long as the pilot remains able to activate the technology. If a pilot is spatially disoriented but remains unable to initiate PARS, Auto-GCAS should theoretically still save him/her from CFIT. The other big killer, the notorious G-LOC (For more info on Pulling G’s see this post), is expected to occur less frequently with incorporation of the newer, more effective G-suit called ATAGS, but Auto-GCAS will also play a role to save pilot and aircraft if G-LOC were to occur. Lastly, gear up landings in any aircraft utilizing this technology should no longer occur.
Ground Collision Avoidance Technology has some significant software and hardware limitations. For example, the system is not able to make inputs on the throttle. If the throttle is in idle upon activation, the aircraft will quickly lose maneuverability and control authority. This will limit the efficiency and ability for inputs of the flight controls to produce their desired effect. In other cases, a reduction in power may be required for the optimal recovery. Pilots have been trained on this new system and are aware of these limitations. If the GCAT systems find that they are unable to initiate recovery due to the current throttle setting, all it can do is notify the pilot.
Although this technology will undoubtedly give fighter pilot spouses reason to sleep more peacefully, possible exceptional circumstances in which the Auto-GCAS cannot prevent CFIT still exist. The recent loss of an F-16 and death of Capt. Will “Pyro” DuBois after installation of GCAT remains a tragic example of the fact that even though new technologies are creating significant strides in safety, the risk inherent to combat aviation will always be present.
Top image credit: NASA