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Old 26th Sep 2007, 00:07
  #2451 (permalink)  
alf5071h
 
Join Date: Jul 2003
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RWA thanks for the update (#2363). I agree that the recommendation is logical in the context of the TransAsia accident, and I am not questioning the report. The Retard call is not a ‘warning’ in the normal design sense, it is an advisory call similar to that which could be given by PNF, which can stop at any time (or even be omitted).
Some views consider the call unnecessary. During normal operations a thrust lever asymmetry might be best detected by the failure to achieve reverse, a condition for which the crew are alerted.
Problems arise when one reverse is MELed and when using the old crew procedure, aspects which have been discussed previously.
Thus, (with positive speculation), if Airbus considered alternative means of alerting and discussed these as options with the Taiwanese, they could have been reported as either proposals for action (planned action) or just considerations for other methods for remedial action; I doubt that we can fully understand this or anything else which could have been be lost in translation.

With further speculation, Airbus may have concluded that as the recommendation was only ‘to review’, and that the primary finding in the accident report related to training and crew co-operation, then a training solution (procedural) had greater relevance. Hence the change to the MEL DDG procedure requiring both TLs to be selected to reverse.
The procedural solution might be seen as having advantages of not changing normal operations, and (as I understand the system), provide an additional awareness / error check during MEL ops; i.e. both TL in REV results in 2 annunciations (amber/green). The procedure addressed the problem directly (crew not moving TL) and did not stick a ‘band-aid alert’ over the error.
I am not debating the pros or cons of thinking this way, nor suggesting that a procedure is better than a design change, but these are the type of issues that design teams, safety pilots and management (humans, subject to HF) have to judge at that time. Thus the speculation might aid some contributors to consider how a manufacturer might address the problem at that time and provide a response based on information in the accident report.
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