- "Controlled flight into terrain" is one of
aviation's greatest fears of all. Initial indications surrounding the
loss of Crossair flight LX 3597 last Saturday seem to suggest an
accident of this kind. Just four days later, a similar incident
occurred in Nigeria involving a Boeing 747 freighter. In view of the
danger, systems have been specially developed over the years to warn
the pilots in good time if they are flying too close to the ground.
Crossair is at the forefront in implementing these developments.
GPWS is the name given to on-board systems of this kind. GPWS
stands for "Ground Proximity Warning System". The GPWS monitors the
aircraft's descent rate in relation to its height above the ground.
If it senses that the aircraft is getting dangerously close to the
terrain, the system will generate a "computer-voice" warning. The
system will also issue an alert if the aircraft descends below the
minimum altitude specified for a particular phase of flight. The GPWS
obtains most of its information from the aircraft's radio altimeters.
GPWS is installed in 13 700 jet aircraft and 7 000 turboprop
transports all over the world, and is carried by every aircraft in
the Crossair fleet.
Technology is now taking these precautions a step further. EGPWS,
or the "Enhanced Ground Proximity Warning System", is additionally
provided with a "memory" of the topography of the terrain being
overflown. This enables the system to "look ahead" and give the
pilots far more advanced warning of any danger which may arise.
EGPWS also features a colour-screen display of the area concerned,
with critical points marked in red.
EGPWS features very recent technology: indeed, it will only be
specified as standard for new aircraft from April 2002 onwards. But
many airlines are choosing to install the new equipment voluntarily
on their fleets. At Crossair, EGPWS is provided on all the company's
Embraer jets. It is also carried on four Avro RJ100 Jumbolinos, and
will be installed on the rest of the Jumbolino fleet as they come in
for their regular maintenance checks. EGPWS is currently carried by
some 4 400 of the more than 20 000 commercial aircraft which are
currently in service around the world. The system will be mandatory
on all civil aircraft from 2005.
Despite all these safety systems, incidents can still occur. And
disasters can also occur when errors or misunderstandings arise in
the interplay between man and machine.
ots Originaltext: Crossair
Crossair, Corporate Communications
P.O. Box, 4002 Basel, Switzerland
Phone: +41 61 325 4550 or +41 61 325 3437
Fax +41 61 325 3554