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737 left roll and pitch up despite forward column and full right ailerons

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  • 737 left roll and pitch up despite forward column and full right ailerons

    Sounds like icing to me:

    A Canadian North Boeing 737-300, registration C-FGCN performing flight 5T-1517 from Fort MacKay Albian,AB to Edmonton,AB (Canada) with 139 people on board, was climbing through about 800 feet AGL when the aircraft began to uncommandedly roll left. The crew countered by applying full right ailerons, the roll to the left however continued. Airspeed began to decay, the crew applied nose down inputs, however, the aircraft reached a nose up attitude of 28 degrees despite the control column commanding nose down. The airspeed finally recovered and increased permitting the crew to retract the flaps after which the left roll ceased. The crew checked engine parameters and configuration with no anomalies detected and decided to continue the flight to Edmonton for a safe landing with no further anomaly observed.

    The Canadian TSB reported the occurrence for the first time on Jun 23rd 2014 stating, that the weather conditions at Fort MacKay's Albian's Airport were -22 degrees C with moderate snow. Immediately prior to departure the aircraft was de-iced with type I followed by type IV fluid. Departure roll and rotation were normal. According to flight data recorder the aircraft reached a maximum left bank angle despite maximum right ailerons and a pitch attitude of 28 degrees despite the control column in a 10 degrees nose down position. After the speed recovered the crew retracted the flaps, the left roll ceased, the crew checked engine thrust settings and leading edge devices, all parameters were normal. The crew decided to continue the flight to Edmonton without declaring emergency. The crew used a reduced flap setting for landing. The airline and Boeing are further investigating the event.

    --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
    --- Defend what you say with arguments, not by imposing your credentials ---

  • #2
    Is it usual to continue the flight after such an event? I understand that they proceeded with their checklists, and their intelligence and skill are likely what saved them in such a situation, it just seems odd to not return to the airfield.
    Whatever is necessary, is never unwise.

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    • #3
      Originally posted by AA 1818 View Post
      Is it usual to continue the flight after such an event? I understand that they proceeded with their checklists, and their intelligence and skill are likely what saved them in such a situation, it just seems odd to not return to the airfield.
      Note that since the problem corrected when they retracted flaps, they decided to land with partial flaps. Better to go for a longer runway and a lighter weight (after burning fuel). That could explain it.

      --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
      --- Defend what you say with arguments, not by imposing your credentials ---

      Comment


      • #4
        The crew countered by applying full right ailerons, the roll to the left however continued. Airspeed began to decay, the crew applied nose down inputs, however, the aircraft reached a nose up attitude of 28 degrees despite the control column commanding nose down.
        Regarding the bold font...what can one say...why didn't they just firewall the throttles and maintain the normal climb attitude?

        Now for the arm-chair, second guessing, comment on stuff I don't really know about...

        When you are "stalling" (or something similar), isn't there a rule to use rudder since ailerons can exacerbate the stall on the more-stalled wing???

        Of course- we basically don't ever use rudder in flight because there's a yaw damper...

        ...and we even fault pilots for using the rudder in some instances.

        Just a bit conflicting.
        Last edited by 3WE; 2014-06-24, 14:38. Reason: I forgot the blue font on my sarcasm...
        Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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        • #5
          Originally posted by 3WE View Post
          Regarding the bold font...what can one say...why didn't they just firewall the throttles and maintain the normal climb attitude?
          On aircraft with under-wing engines, adding power creates a nose-up pitching tendency. If the plane was already pitching up uncontrollably, they may have been reluctant to add power for fear of making the problem worse.

          Also consider that at 800' AGL on departure, the engines would have been running at close to full power anyway.
          Be alert! America needs more lerts.

          Eric Law

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