Strasbourg A320 crash: "Pilot Error" - Official!

From:         Pete Mellor <pm@csr.city.ac.uk>
Date:         28 Jun 93 22:35:09 PDT
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In France-Soir of Monday 10th May (which was recently sent to me by a 
friend) there is a report that the Commission of Enquiry into the crash of 
an A320 near Strasbourg on 20th January 1992 is about to deliver its 
final report. (Given the date of the report, it has probably already done 
so.) 

The conclusion on the cause of the accident is "pilot error". 

The main error was the confusion of the "flight-path angle" (FPA) and 
"vertical speed" (V/S) modes of descent, selected on the Flight Management 
and Guidance System (FMGS) console. The pilots were inadvertently in V/S 
when they should have been in FPA mode. 

The error was not noticed on the console itself, due to the similarity 
of the number format display in the two modes. The other cues on the 
Primary Flight Display (PFD) screen and elsewhere (e.g., altitude and 
vertical speed indicator) were not noticed since the pilots were 
overloaded following a last-minute change of flight plan, and presumably 
were concentrating on the Navigational Display. 

The actions of the ATC did not help the situation. 

The result was that the aircraft descended at a vertical speed of 
1100 metres/minute when it was only 1500 metres above the terrain. 

Following the accident, the rescue teams took 2 hours to find the crash 
site, which probably led to the deaths of between 6 and 20 passengers who 
had survived the impact, and could have been saved by prompt attention. 

This in turn was partly due to chaotic organisation, plus the fact that the 
emergency radio beacon was destroyed on impact. 

Further details when I have had time to translate the report properly, or 
get hold of a copy of the final report. 

Peter Mellor, Centre for Software Reliability, City University, Northampton 
Sq., London EC1V 0HB, Tel: +44(0)71-477-8422, JANET: p.mellor@csr.city.ac.uk 
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