What happened
On 22 October 2005, an Airbus A319-131, registration G-EUOB, was performing a scheduled passenger flight from London Heathrow to Budapest. During the climb phase at 1926 hrs, the aircraft experienced a major electrical failure involving the loss of the left electrical network. This failure caused the sudden disappearance of the captain's Primary Flight Display (PFD) and Navigation Display (ND), as well as the upper ECAM display. Additionally, most cockpit lighting, the VHF radios, and the intercom became inoperative.
Despite the loss of critical electronic displays, the commander maintained control of the aircraft by flying using the standby instruments and referencing the visible night horizon. The co-pilot performed the necessary abnormal checklist procedures via the lower ECAM display. After approximately 90 seconds, the crew successfully restored most systems by adjusting the AC ESS FEED switch. The aircraft continued its flight to Budapest without any injuries to the 76 passengers or 6 crew members.
The investigation
The AAIB investigation focused on the simultaneous failure of the left electrical network and the co-pilot's flight displays. Investigators examined the aircraft's maintenance history, which showed the aircraft had been maintained according to an approved programme. The investigation also looked into why the incident was not immediately recorded in the aircraft technical log, noting that while the commander filed an Air Safety Report, the technical log only reflected minor, unrelated defects.
Findings
- The primary cause of the incident was the loss of the left electrical network, the specific origin of which could not be determined.
- A secondary, co-incident failure caused the co-pilot's PFD and ND to blank or degrade significantly at the same time as the network loss.
- The flight crew were properly licensed and had complied with all flight time and duty limitations, though they had not received formal training for operating the aircraft solely by reference to standby instruments.
- The aircraft's technical log failed to capture the full significance of the event, as the airline's safety department did not immediately receive the detailed information from the commander's report.
- There is a known failure mode in the A320 family where the co-pilot's displays can fail while leaving the lower ECAM functional, a situation that can lead to a total loss of primary flight information if the left electrical network is also lost.