System alters course if pilot fails to respond; later version could stop deliberate collision

Honeywell is testing a development of its enhanced ground proximity warning system (EGPWS) that allows the automatic flight control system to manoeuvre an aircraft away from colliding with a building or entering restricted airspace, if the pilot does not respond to an alert.

Initially the EGPWS-based assisted recovery system is seen as a safety enhancement for any autopilot-equipped aircraft, but on fly-by-wire airliners the system could be further developed to prevent a deliberate collision by taking control away from the pilot or hijacker, says Honeywell research fellow Howard Glover.

A similar capability could be developed for the air-to-air TCAS traffic alert and collision avoidance system, the company says.

The assisted recovery system now being flight tested in Honeywell's Beech King Air testbed modifies the company's EGPWS by adding data on restricted airspace to the existing digital terrain and obstacle databases, and introducing manoeuvre algorithms to drive the automatic flight control system.

If the EGPWS detects an impending collision with terrain, an obstacle or protected airspace, and the pilot does not respond to the warning within 5s, the autopilot executes a gentle manoeuvre away from the threat. A manoeuvre of less than 0.2g, equivalent to a 30° banked turn, is sufficient, Glover says.

The system guides the aircraft vertically and horizontally, to avoid other airspace restrictions or obstacles during the manoeuvre. "It is not necessarily a simple algorithm, as the aircraft may not be able to climb above protected airspace and may have to thread its way between obstacles," says Glover.

Honeywell believes there have been enough cases of delayed pilot reaction to ground proximity warnings to justify development of the assisted recovery system as a safety enhancement. Security-related temporary flight restrictions are also making airspace more complex. The safety system could be available within two years, Glover says.

Honeywell is working with Boeing Phantom Works and NASA to develop an EGPWS-based system to prevent fly-by-wire aircraft entering no-fly zones around sensitive locations. The security system will be flown on NASA's Boeing 757 testbed within two years, Glover says.

Source: Flight International