Technology which could take over control from terrorist pilots might create greater risks than it eliminates. Suggestions about how technology could take control from pilots in the event that flight-qualified terrorists get into a flight deck again have become popular among commentators, but aircraft and avionics manufacturers are not joining in.

Jim Coyne, president of the US National Air Transportation Association, was one of many who proposed that future aircraft should be able to be flown from the ground with the control input of people in the cockpit negated. Manufacturers - not happy to be quoted - have countered that being able to take control of aircraft from the ground would be the stuff that terrorists' dreams are made of. Anyone, they say, capable of replicating the datalinks necessary to carry this out could create disaster without the need to become a martyr.

The other serious objection raised is that if the technology developed a fault it could cause accidents by intervening at a critical time when there was no hijack and the flight was proceeding safely.

An outwardly more plausible system - not proposed by the manufacturers - is linking a developed version of the Honeywell enhanced ground proximity warning system (EGPWS) into the flight envelope protection system (FEPS) in fly-by-wire airliners. This would make it impossible to fly aircraft into buildings because the aircraft would automatically turn away or climb to avoid them. This assumes that the fly-by-wire FEPS system was the Airbus type, as in the Boeing 777 the pilots can directly override the flight envelope protection system. Even in an Airbus, if the pilots selected direct control law instead of normal, or if they cut the fuel to the engines, which would result in the same thing (as well as forcing the pilots to glide), they could cut out the FEPS.

Honeywell says only that the fundamental tenet of all certification authorities is that no one system or component fault should be able to bring down an aircraft, so any system able to take total control of an aircraft would require a level of integrity entailing multiplexing in all its components and data inputs, probably with a voting system.

Airbus says its control philosophy is that all important manoeuvres or system selections must be the result of pilot action. Changing that, it says, would require a completely different approach by the certification authorities. The manufacturer adds that it has a team working on possible solutions to the terrorism threat, but that the best protection is to prevent hijackers getting on to the aircraft.

EADS, the majority shareholder in Airbus, says it is looking at the possibilities of harnessing its areas of expertise to see if it can find systems to defeat hijack attempts. These include encryption, unmanned air vehicles, flight management systems, information management, and communications, command and control systems.

Source: Flight International