Incident Overview
On 22 October 2005 at 1926 UTC, an Airbus A319-131 (registration G-EUOB) was climbing through approximately FL200 in clear weather conditions near Clacton, Essex, during a scheduled flight from London Heathrow to Budapest. The crew heard an audible ‘CLUNK’ and the flight deck became dark, accompanied by the loss of multiple electrical systems and flight information displays.
Cockpit Symptoms and Crew Response
The following systems were lost: Captain’s and First Officer’s Primary Flight Displays, Navigation Displays, and the upper ECAM display, leaving only the lower ECAM display available. The Autopilot and Autothrust systems disengaged with associated aural warnings. Intercom and most flight deck lighting, including integral lights on the glareshield, overhead, and pedestal panels, also failed.
The commander, who was the Pilot Flying, took manual control and maintained aircraft attitude by referencing the external night horizon, the standby horizon, and other standby instruments that were visible. The electrically driven standby horizon was not powered or lighted at the time, but according to the flight manual, it remains usable for 5 minutes without power. The commander transmitted a ‘MAYDAY’ call on VHF No 1, but it was not received by Air Traffic Control because the radio was unpowered.
The First Officer carried out the ECAM actions, which included selecting the ‘AC ESS FEED’ push button switch. The primary flight instruments and most other systems were restored approximately two minutes later. Communication with ATC was regained, and the crew requested a holding pattern to review the aircraft status. After completing ECAM actions, several systems remained inoperative, including the No 1 Transformer Rectifier unit and the Captain’s windshield and window heat.
The aircraft held for about 40 minutes before continuing to Budapest, where the First Officer performed the landing. During the landing roll, the crew noted a No 1 thrust reverser amber caution. After landing, a maintenance engineer successfully reset all remaining affected systems. The aircraft operated for six more days with no further electrical failures reported.
Investigation
The incident came to the attention of the Air Accidents Investigation Branch through the UK Mandatory Occurrence Reporting Scheme. The aircraft was taken out of service for investigation under AAIB supervision. Troubleshooting actions included integrity checks of the electrical power system and inspection of the Integrated Drive Generator feeder connectors located in the engine pylons; these tests did not reveal any anomalies.
The No 1 Generator Control Unit, three Display Management Computers, the No 2 System Data Acquisition Concentrator unit, and the No 2 Flight Warning Computer were removed for investigation. The aircraft was returned to service and continued operation without further reports of similar malfunctions.
Summary
The flight crew lost all primary flight instrument displays and used both the visual horizon and the standby horizon for attitude reference. The standby horizon, which was unpowered, would only have been available for 5 minutes. The AAIB is investigating this incident with the cooperation of the aircraft manufacturer and the operator. A further report will be published when the investigation is complete.