What happened
On 15 September 2006, an Airbus A319-111, registration G-EZAC, was operating a flight from London Stansted to Alicante, Spain. During the flight, the aircraft experienced a significant electrical power disruption involving the loss of AC BUS 1 and the AC ESS busbar. This failure had a cascading effect on various aircraft systems, including the degradation of the Electronic Instrument System and the loss of several critical flight instruments.
Crucially, the electrical failure led to the loss of all Radio Telephony communications, leaving the crew unable to communicate with Air Traffic Control via standard VHF channels. The crew had to manage the aircraft through a complex series of system failures while navigating the airspace near Nantes, France.
The investigation
The AAIB investigation focused on the electrical power generation system and the specific behavior of the aircraft's busbars during the event. Investigators examined the functionality of the Generator Control Unit (GCU) and the Ground and Auxiliary Power Control Unit (GAPCU). The probe also looked into the impact of the failure on the Electronic Instrument System and the subsequent loss of communication capabilities. The investigation reviewed maintenance history, specifically looking at recent activity and the status of the aircraft's electrical components prior to the incident.