AAIB investigation to Airbus A319-131, G-EUPS

Shortly after takeoff from Edinburgh Airport, the Autopilot (AP) and Autothrust (A/THR) systems disconnected during the climb, followed by a loss of positional information from the Global Positioning Inertial Reference System (GPIRS). The flight crew initially declared a PAN and the flight continued to London Heathrow Airport using radar vectors. The flight crew were able to re-engage the AP and A/THR systems, but they disconnected again during the approach and a further rudder travel limiter system error immediately prior to landing necessitated a go-around. The aircraft subsequently landed safely.

The AP and A/THR disconnects and the loss of the GPIRS and rudder travel limiter systems were caused by severe drift of the aircraft’s Inertial Reference System (IRS) due to vertical shock loads encountered during the takeoff roll at Edinburgh. The exact source of the shock loading was not determined but two larger sound impulses from the nose landing gear were captured by the Cockpit Voice Recorder (CVR). No damage or irregularity was found with the Air Data Inertial Reference Units (ADIRU) or the Nose Landing Gear (NLG).