An anti-terrorist flight mode installed on commercial aircraft could prevent a repeat of attacks like those on the World Trade Center and the Pentagon, experts have claimed.
A system to take control of a hijacked aircraft away from the flight deck and land the aircraft automatically at a safe airfield is feasible using current technology, said its proposer, instrumentation engineer and pilot Geoff Harris. Harris has already contacted Airbus with the proposals.
Using the system, a captain suspecting imminent hijack would press a button putting the aircraft on autopilot, disabling the flight deck controls.
A preset flight plan would then be activated in the plane’s flight computer, which would route it to the closest suitable airfield by the quickest and safest route. This route would be clear of towns to allow the aircraft to dump fuel, and prevent loss of life on the ground if the hijackers had smuggled a bomb on board.
The manual controls could not be re-activated from the flight deck, but only from the ground using a strongly encrypted signal sent by air traffic control.
‘This signal would only be issued if the air traffic controller was satisfied the hijackers were under control. The plane could not be taken off autopilot by a hijacker, preventing tragedies such as the World Trade Center attacks,’ said Harris.
A similar signal to take control of the plane could also be issued by air traffic control if an aircraft were spotted deviating from its flight plan, or behaving strangely, in the event of aircrew being attacked before they had a chance to press the hijack button.The aircraft would land automatically using the Integrated Landing System (ILS), which employs sensors on the airstrip that are detected by aircraft, allowing it to be manoeuvred into the correct approach position. Once on the ground, the plane would be met by specialist military units who would have a chance to rescue the passengers and crew.
‘With some effort this could be put on to all airliners very quickly. Given vigilance to ensure that explosives do not get on board, it would make hijack all but impossible,’ said Harris, who has 30 years’ experience in sectors including avionics.
Some experts caution that the system could also allow hackers to gain control of the aircraft from the ground. But Harris said the signal would be so strongly encrypted it would not be easily detectable, and would only be used very rarely, giving hackers no chance to analyse the code.
‘Planes have been flying using autopilot for many years. This would be designed to be safe, and would use existing technology. When terrorists realise aircraft have this system, they would not hijack planes in the first place, because there would be no point.’
The idea has already been debated by academics, according to Dr Colin Goodchild, senior lecturer in avionics systems at Glasgow University. The technology to direct aircraft from the ground can be easily developed, while the means to provide information on diverting to alternative airstrips already exists, he said. ‘The technology is there. It is a feasible way of preventing a terrorist from controlling an aircraft, by removing control from the aircraft itself.’
Sophisticated pilotless aircraft are already being flown around the world, for use mainly by the military, but the technology has not yet been applied in such a way to commercial aircraft because nobody imagined passengers would be sacrificed for use as a weapon, he said.
Passengers may also have found it hard to accept that no one on board the aircraft was actually in charge of the controls, but the events in the US may have changed public perceptions. ‘It is better to have control from the ground than control by someone attempting suicide.’
Fitting new equipment to all aircraft in service could be an expensive business, and many fear airlines, already hit by falling passenger demand for flights and the extra cost of extra security at check-in, could be unwilling or unable to pay for it.
But the technology needed to implement this anti-terrorist mode, such as more precise navigation systems and controls, would probably be fitted over the next few years in any case, said Goodchild, and the technology to land automatically has existed since 1948. ‘This is not a research activity, it is a development activity.’
A spokeswoman for Airbus said the idea would be considered, along with a number of other suggestions being looked at by the industry.
These suggestions include armed air marshals on every flight, and locking the door to the flight deck to prevent the pilot being lured away from the controls.