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Old 20th Oct 2002, 13:17
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Centaurus
 
Join Date: Jun 2000
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Checklist Challenge and Response theory.

Boeing 737 advice on challenge and response infers (for example) that PNF reads "Landing Gear". And PF checks visually for lights and lever and responds "Down and Three Greens"

Or another one. On final PF calls for landing flap. When action is completed, the PNF calls one word "Flaps" - and waits for the response -which may be "Thirty Green Light.

This policy correctly forces the responder to physically check the position and indication before responding. If the response is wrong - then the PNF picks him up and action is taken to correct the problem.

If, however, the policy is changed to the PNF reading the challenge and also giving the response before the PF gives his response, then the challenge and response theory is compromised, because it is possible for the PF to parrot back the response given by the PNF without checking.

Can anyone offer advice therefore, on why, in a Non-Normal checklist where Boeing advocate that the PNF both challenges and responds to a switch or lever position, the landing check (for instance) of Gear Down and Three Greens, is challenged AND responded by the PNF as well as responded again by the PF.

Is this not only a checklist overkill, but also a misinterpretation of the Boeing intent - which by the design of the Normal Procedures philosophy, requires an independant non-prompted response by the PF?

In other words, why in the 737 Non-Normal landing checklist does the PNF put words into the mouth of the PF by announcing the what the response should be? Or have I got it all wrong?
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