The operational modes

The exceptional situation is defined by a combination of modes belonging to two mode sets :

• The primary mode set: the operation was for  pushback, taxi, takeoff, cruise, descend, final approach, landing., etc.. Formally, the operation mode could be defined as a member of the mode set ( pushback, taxi, takeoff, cruise, descend, final approach, landing.)
• The safety mode set: this mode set could be controlled by the operator, but it was changed automatically to "Envelop Protection", designed to prevent stalling.

  In the particular accident, the protection was by disabling the throttle, and therefore the pilot was not able to complete the flyover. .

  The failure in this case study is attributed to scenario ambiguity, due to implicit setting of the safety mode.

  To enable identification of scenario mismatch, the modes should be defined explicitly, and the Scenario analyzer should verify that they match.

  Guidelines about mode setting

Updated on 17 May 2016.