2 responses to The C* continuum

    Gus Audiber 08/02/2015 at 9:20 am

    “a similar scenario of a stabiliser auto-trimming delaying recovery of the aircraft from a stall condition doomed the crew of Airways Germany flight 888T only a few months before (BEA 2010).”

    In this accident they were in “Direct Law” (read BEA report again)
    In “Direct Law” the trimming of the stabiliser is no automatic .. it’s manual


      Matthew Squair 08/02/2015 at 1:25 pm

      Correct, remember that prior to Direct (abnormal attitude) they were in modes in which Auto trim operates and it had already trimmed the stabiliser to max. From the BEA report (p49):

      “From 15 h 44 min 30 the automatic trim function displaced the stabiliser as far as the electric nose-up thrust stop (- 11 degrees). The stall warning sounded at 15 h 45 min 05. The nose down commands applied by the Captain on the sidestick brought the elevators, due to the load factor, to the neutral position, without however pushing them to the stops(25). Consequently, the trimmable stabilizer did
      not move even though the flight control law was normal.

      From 15 h 45 min 15 until the end of the flight, the automatic trim function remained unavailable. In fact, the direct law was active from 15 h 45 min 15 to 15 h 45 min 40 and the Abnormal attitude law phase 1 (without auto-trim) remained active till theend of the flight.”