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So I was reading about Garuda Indonesia Flight 152 and one of the reason it crashed was for a GPWS malfunction. Here is the Wikipedia article about the crash and GPWS: Garuda Indonesia Flight 152

The plaintiffs alleged that the GPWS was defectively designed, that the manufacturer was aware of its deficiencies in mountainous terrain for over a decade, and had the system worked as designed the accident could have been avoided.

Was this problem ever fixed? Did Hamilton Sundstrand Corporation fix the problem? Also I was wondering if anybody knows what company makes the GPWS for an Airbus A350 and an Airbus A320?

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    $\begingroup$ GPWS is considered obsolete and was phased out in the early 2000s. $\endgroup$ – user71659 Feb 27 '18 at 21:20
  • $\begingroup$ Despite what the Wikipedia article states, Hamilton Sundstrand did not make the GPWS. Sundstrand Data Control built the GPWS. Sundstrand Data Control was purchased by AlliedSignal in 1993 from Sundstrand Corporation. AlliedSignal later purchased Honeywell International in 1999, taking the Honeywell name. Honeywell is the current owner of the GPWS/EGPWS product line. Sundstrand Corporation was purchased by UTC in 1999 and merged with Hamilton Standard to become Hamilton Sundstrand under UTC. $\endgroup$ – Gerry Apr 3 '18 at 13:24
  • $\begingroup$ @user71659: GWPS itself is not obsolete. The earlier forms of GPWS are obsolete - EGPWS/TAWS is still a form of GPWS. $\endgroup$ – Sean Jun 3 '18 at 22:48
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EGPWS/TAWS is the fix for this problem...

The original Ground Proximity Warning Systems were indeed quite limited due to their inability to know anything about anything besides what was under the plane at the time. While one could theoretically use ground-mapping radar techniques similar to military terrain following radar for this, that would be dancing in a minefield of classification and relatively advanced signal processing, making it impractical for use in the civil aviation environment.

Instead, EGPWS (enhanced ground proximity warning system)/TAWS uses the aircraft's idea of its own position (from the onboard navigation systems) along with a database of terrain info to generate forward looking warnings in addition to the more straightforward radio-altimeter warnings generated by GPWS. This is what is found on basically all aircraft in mainline airline service these days, as well as many more modern business jets and commuter-type aircraft as well.

but even TAWS won't save you if you're getting lied to about where you are!

Nonetheless, it's still possible to have a non-pilot-error CFIT in an EGPWS/TAWS equipped aircraft -- on one fateful day in Ethiopia, a British Mediterranean Airlines A320 nearly became a crater twice over thanks to the ADS VOR/DME providing bad bearing information to anyone who tried to use it as a navaid -- without GPS, the only thing the TAWS had to go on was the VOR-updated IRU position, which was being thrown off by the bad data from the ADS VOR. Luckily for the passengers, the crew had their wits about them and caught the situation before smashing into the ground, but even with GPS being nearly universal in airliners compared to its prevalence in 2003, interference, spoofing, or jamming of GPS signals is still a threat, as this year's Red Flag exercises are reminding us quite vividly by taking out GPS service across much of the western CONUS.

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