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Old 30th Sep 2016, 18:03
  #1140 (permalink)  
alf5071h
 
Join Date: Jul 2003
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Uplinker,
Take care not to extent your experience too far. Detecting unusual speed tape behaviour depends on having a datum; what is 'unusual', when to act, the dividing line between normal and abnormal.

EFIS sensor failures are usually clear cut - blank display / red flag. Another form of failure is the state of 'no computed data', where the sensor is working but not outputting valid data.
In all of these cases the manufacturer has to undertake a risk assessment and only then as necessary provide a crew drill for rectification or risk mitigation.

However, in the event of unusual system behaviours without alerts or warning (very very unusual, i.e. low risk) then crew intervention might be required; but given system reliability and certification requirements it would be more likely that the situation has been miss assessed;- "what have I misunderstood or not seen".

Most abnormal drills only apply to the situation as defined by the manufacturer; do not attempt to fit a procedure to a situation.
Infrequently pilots will encounter situations where their assessments are inaccurate and thus choose an inappropriate procedure; a situation and reasoning which you eruditely recalled from your simulator experience.

The lesson to be learnt is to reassess a situation, particularly if the chosen drill is ineffective.
But how long to wait, how much time is available, what else to check, ... such is the pilots burden, experience, knowledge, judgement.

But all is not lost; with diligent observation pilots can store knowledge of what is 'normal' (a datum), which can help in the very rare situations.
We would be unfortunate to encounter one of these in a career ... except those, in one form or another, which do exist, more often generated by ourselves; and because of this they involve mind numbing surprise and reluctance to change.
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