The pilot of a Saab 2000 unknowingly attempted to override the aircraft’s autopilot during a December 2014 flight control incident inbound to Sumburgh airport in the Shetland Islands, according to a preliminary report from the UK's Air Accidents Investigation Branch. The Saab had earlier been struck by lightning while on approach to Sumburgh, after which the pilot in command (PIC) believed the aircraft was no longer responding to pitch commands as he expected it to.

The flight data recorder showed that after reaching 4,000 feet in a subsequent climb, the aircraft pitched nose-down to a minimum of 19 degrees, exceeding the maximum operating speed by 80 kias with a peak descent rate of 9,500 fpm. The aircraft again began to climb after descending to just 1,100 feet. Recorded data showed the autopilot had remained engaged and the autopilot pitch countered the pilots’ nose-up pitch inputs trim function that made a prolonged nose-down input in an attempt to maintain its altitude-tracking function. The PIC still believed there was a control problem and called for the first officer to pull the pitch disconnect, which he did.

The crew diverted to Aberdeen, where they made a successful landing. None of the 33 people aboard the aircraft was injured during the incident.