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Old 24th Mar 2004, 16:01
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alf5071h
 
Join Date: Jul 2003
Location: An Island Province
Posts: 1,074
Bumz_Rush Try search low temperature correction.
Also see:
http://www.faa.gov/language/accold.pdf
http://www.bluecoat.org/reports/Long_98_Cold.pdf
http://www.fmcguide.com/media/calgary.pdf

It is surprising how often this subject appears in this forum; this begs the question is the subject taught, and if so how or when is it remembered. Was it fully understood? Furthermore, the many links and references tell what the corrections are, but few tell where or when to use them. Is the industry complacent in these matters, who next will to be caught out by the failure to correct the altimeter and what risk is there of a CFIT event if EGPWS is not fitted?

A recent FSF conference paper reviewed the use of geometric altitude (GPS based) in the EGPWS; this facility shows the true altitude on the EGPWS display (ND), but does not correct the main altimeters. Thus if there is a difference between geometric and the main altimeters then start thinking about cold temp correction or recheck that you have the correct pressure setting. The speaker at FSF also noted the poor understanding that crews have of the actual equipment fit EGPWS with or without geometric altitude, navigation input GPS or FMS RNAV (FMS RNAV operators beware of potential errors - Addis Ababa event). Also of note were the poor updating of software standards and terrain databases; all free from the manufacturer http://www.egpws.com.

Do the issues above suggest that operators are under strain in the training and knowledge area?
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