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Old 16th Sep 2016, 06:30
  #1568 (permalink)  
safetypee
 
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RAT, RAAS should only give a Long Landing alert in the air; see http://www.pprune.org/tech-log/58438...ml#post9507540
The concern, the effect of an apparent alert on the ground, which may apply in this accident (and probably is what you implied) is that a 'valid' RAAS alert could be given in the air, and where SOPs demand a GA it requires a late non-standard version of the GA procedure, however, by the time (short time) TOGA is selected the automatic TOGA function is no longer available as the aircraft is effectively on the ground (<2ft) which requires a completely different rejected landing procedure. (#1525) Confusing, yes ?

The position accuracy comments are interesting; presumable such errors are function of the GPS performance and/or system input (see previous comments on GPS Nav input vs internal GPS from EGPWS).

RAAS is a very good safety concept, but one wonders if it has been pushed a bit too far for landing performance due to system accuracy, aircraft installation/FGS interface, and how it is used (choice of SOP).
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