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Auto-GCAS approved for block 40 F-16s

October 15, 2009 (by Asif Shamim) - According to Flightglobal, the USAF has finally approved funding for the Automatic Ground Collision Avoidance System (Auto-GCAS) to be fitted to F-16 Block 40s, with future additions to the Lockheed F-22 & F-35.

USAF F-16D block 25, #83176, used for the combined US-Swedish GCAS trials, held in 1998 [USAF photo]

Auto-GCAS is a software application that keeps track of the aircraft's position, speed and altitude against a digital terrain map of the Earth.

The system generates a warning alarm seconds before taking over from the pilot should they disoriented, or suffers a g-induced loss of consciousness (G-LOC). The pilot has les than 2 seconds to respond to alarm otherwise the software rolls the aircraft violently to a wings-level orientation and then initiates a 5g pull-up. The computer returns control back to the pilot after it restores the aircraft's stability.

The software algorithms are designed in such a way that its does not interfere with the pilot's mission, said Mark "Tex" Wilkins, a retired USAF colonel now working as senior aviation safety analyst .

A particular concern is high-angle strafing attacks. Pilots do not want the computer to take control at the wrong time. The pilot has the ability to set a minimum altitude depending on the mission being flown. The software only kicks in when the jet flies below the set height.

If the system were installed across the fleet today, it would have saved the life of Capt George Bryan Houghton, who died on 22 June after losing track of his altitude, Wilkins says.

According to the USAF mishap report, Houghton was practising high-angle strafing attacks at night in the F-16, an aircraft relatively new to his experience. The report concluded that Houghton focused too intently on the laser spot illuminating his target as he began to dive. Houghton failed to respond to any of three different cockpit alert systems - and urgent calls by a ground controller - telling him to "pull up".

In addition, flight-test activity should not pose problems for Auto-GCAS, Wilkins says, citing the fatal F-22 accident in March involving Lockheed test pilot David Cooley. He was performing a high-g manoeuvre to collect a test point, but briefly suffered a condition known as "almost g-induced loss of consciousness", according to the USAF mishap report. By the time he regained awareness, the F-22 was in an unrecoverable position, diving through 14,000ft (4,267m) at Mach 1.6.

In this, auto-GCAS would not have interfered while Cooley performed the high-g manoeuvre, Wilkins says. "Auto-GCAS was fine with that," he says. "But when he pulled the nose down there, and hit somewhere around 70° nose-low, that's when auto-GCAS kicks in."

Auto-GCAS has been developed over the past 25 years between NASA, the Air Force Research Laboratory and Lockheed Martin's Skunk Works and will finally be deployed on F-16 Block 40s and above after 2012,

The upgrade is included in the 6.2 block upgrade for the F-16 operational flight programme, Wilkins says.

The technology behind auto-GAS has been about since mid-80's. Pilots have expressed concerns about turning there jets over to computers. But the USAF have weighed up pro's & cons with the technology and have gone ahead in the hope it reduces the mishap rates, particularly as the tactical aircraft is projected to dwindle over the next few decades.