Ground collision avoidance systems are not new. Many existing fighters and bombers include one sort or another of these systems. The main drawback of existing systems is that they only warn the pilot that a collision is about to occur if preventative measures will not be used. The Auto-GCAS is a completely new concept taking the control from the pilot in critical moments and transferring it to the computer. 

Initially, many pilots were extremely skeptic regarding a fully automatic system taking control over their craft at a crucial moment. However, after more than two decades of development and 2,500 automated recoveries against a background of flat terrain and complex topographies, the Auto-GCAS was finally declared ready for operational deployment with more than 98% effectiveness (no info was given regarding the remaining 2%). 

In order to avoid a collision, the Auto-GCAS evaluates a variety of factors including the aircraft's weight, performance, navigation positional information, Global Positioning System (GPS data) and digital terrain elevation data. The system uses this information to constantly calculate the aircraft’s 3-D position relative to the ground, the amount of time available before impact, and the maneuver required to prevent a collision with the ground. 

The researchers used a modified block 25 F-16D to perform flight tests of the Auto-GCAS system.

Whenever the Auto-GCAS system determines that a collision is imminent, meaning that the plane is within 1.5 seconds of the "point of no return" and no action has been taken yet by the pilot, the system will take control and perform an automatic rescue maneuver. The Auto-GCAS is the result of long-term collaboration between the US Air Force, Lockheed Martin, NASA and the Swedish Air Force Advanced Fighter Technology Integration (AFTI). From analyzing previous incidents, the research team realized that because situations such as pilot spatial disorientation, loss of situation awareness (or even loss of consciousness) and G-induced blackouts, can render a pilot unable to process warning signals and perform the necessary maneuvers to prevent a collision with the ground, an automatic system is required. 

Now it remains to be seen when the new system will enter service, how pilots will react to it and most importantly how successful it will be in reducing the number of ground collisions (an average of 4-5 accidents taking place every year for the past 20 years or so). 

More information on the Auto-GCAS program can be found at the U.S. Department of Defense website.