Bernie Fitzsimmons/LONDON
AMERICAN AIRLINES plans to join British Airways and United Airlines in trials of AlliedSignal's enhanced ground-proximity warning system (EGPWS), which the manufacturer plans to start delivering by the third quarter of this year (Flight International, 21-27 February).
American has already decided to test the system on the Boeing 757 and 767, and will probably add the McDonnell Douglas Super 80 to the tests. Also under consideration are trials on a Fokker 100 and an Airbus A300-600+. BA already has a system installed on a Boeing 747-400, and United will equip 20 Airbus A320s. American's loss of a 757 at Cali, Colombia, has added a new urgency to the issue.
American's lead technical pilot, Barry Trudeau, says that the airline is "seriously considering" a fleet-wide fit. "We see this as a very large safety enhancement, considering some of the places we fly to, but we're not going to make a buy without a rigorous testing programme," he insists.
Operators attending a meeting at AlliedSignal's Redmond, Washington, factory on 7 March agreed a two-phase implementation programme, with Phase 1 installations using a separate flightdeck switch to call up the visual display of high ground in the aircraft's vicinity.
Phase 2 systems will be integrated with the avionics, of aircraft equipped with electronic-flight-instrument-systems and will include a look down mode for use when a fault at cruising altitude demands that the crew descend over mountainous terrain.
In both cases, the display will appear automatically in the event of a warning, accompanied by a spoken "terrain, terrain ahead" caution about 60s before a projected impact and "terrain ahead, pull up" at 30s. AlliedSignal will also offer an optional global-positioning-system card to verify the flight-management computer data in areas where updates are not readily available.
The airframe manufacturers appear to have reservations, however. Airbus is reportedly unhappy with the "pull-up" call-out, while Boeing does not want the terrain display to pop up automatically in place of the weather-radar picture.
Trudeau's view is that "...cumular granite is a lot more deadly than cumulo-nimbus", while the pull-up command is familiar from 20 years of GPWS operation. The meeting ended with the two sides agreeing to disagree. He says: "We're trying to get it on as a forward-fit item, but we'll do it ourselves if we have to."
There are also unresolved certification issues, Trudeau says, notably over whether the system should be certificated as an alerting device or as a navigation source.
Source: Flight International
