Originally Posted by
Linerider
Not neccessarily.
13,000ft is barometric altitude, but the GPWS uses the radio altimeter. There could be mountain peaks in that area which triggered it. I don't know that to be the case, just offering a possible explanation.
I looked it up and found a page of "a320 flash cards" which details the GPWS modes and alerts.
GPWS BASIC MODES
MODE 1: EXCESSIVE RATE OF DESCENT
Mode 1 has two boundaries. Penetration of the first boundary (2450 feet radio altitude) generates a repeated "SINK RATE" aural alert...
So a peak of 10550' would trigger the "Sink Rate" alert at 13000'.