Originally Posted by
Takwis
What does TBC-19, the Boeing Flight Crew Operations Manual Bulletin, say you should do when there is an AOA disagreement?
Not that I agree, but they make no mention of an unreliable airspeed checklist...they jump right into fixing the trim problem.
Had to go look up TBC-19. The information was incorporated into our company manuals a little differently, but it is essentially the same guidance. This supplement specifically discusses the impact of an erroneous AOA on the
trim system.
It does not address the effect of erroneous AOA (particularly of the "stall" variety) on other aircraft systems - of which there are quite a few. The crew still needs to deal with those problems, and we have existing procedures for most (but not all) of them. Unreliable airspeed is one of the outcomes of the AOA failure, but we have a NNC that is (mostly) suitable and thus did not need to be modified. Other than the erroneous stick shaker (for which there is no checklist) unreliable airspeed was the
first manifestation of the AOA failure and should have been dealt with first.
A careful reading of TBC-19 basically states that a bad AOA input can create unwanted stab trim movement, and the proper response to the unwanted stab movement is to execute the Runaway Stabilizer Trim checklist. I might add that functionally while experiencing this malfunction in the air, we do not refer to this document (or its equivalent). We refer to the appropriate non-normal checklist.