What happened
On 10 March 2023, a Boeing 787-9, registration A9C-FG, operated by Gulf Air was performing a scheduled flight from Bahrain International Airport to Dubai International Airport. The flight was carrying 183 passengers and 10 crew members. During the descent phase while approaching Dubai, the aircraft experienced a simultaneous malfunction of the left, center, and right Tuning Control Panels (TCP).
This hardware failure triggered a cascade of secondary system issues, including the loss of the transponder, weather radar, and the Traffic Collision Avoidance System (TCAS). The malfunction also prevented the flight crew from changing radio frequencies. While the crew managed to maintain contact with Dubai Approach using a standby radio frequency, the loss of the transponder meant air traffic controllers could no longer monitor the aircraft's movement via radar. After entering a holding pattern and attempting to troubleshoot the systems, the crew declared a radio communication emergency. The aircraft landed safely on runway 12L, and emergency services were present on standby.
The investigation
The UAE Air Accident Investigation Sector (AAIS) examined the flight data recorder (DFDR) and the aircraft's maintenance history. The investigation focused on why the crew was unable to restore the communication systems using available onboard resources. Investigators reviewed the Electronic Flight Bag (EFB) and the Flight Crew Operations Manual (FCOM) to determine if reset procedures were accessible to the pilots. The investigation also looked into the crew's adherence to pre-flight briefing protocols regarding the review of active operational bulletins.
Findings
- The simultaneous failure of all three Tuning Control Panels caused the loss of critical navigation and communication interfaces, including the transponder and TCAS.
- The crew was unable to recover the system because the Copilot could not locate the specific reset instructions within the electronic flight manual.
- The crew did not follow the standard take-off briefing procedure, which includes verifying the most recent flight crew operations bulletins and NOTAM supplements.
- The failure to check for the relevant bulletin (GUL-38 R1) prevented the crew from implementing the necessary reset steps that would have restored the TCP functionality.
- Maintenance personnel were later able to restore the TCPs to full functionality via a manual reset and ground testing.
Safety action
Following the investigation, Gulf Air implemented several safety measures, including integrating FCOM bulletin reviews into type rating courses and distributing a Flight Crew Operations Notice to all pilots. The AAIS issued a safety recommendation (SR14/2024) advising the operator to improve procedures for checking and adhering to operational bulletins during take-off briefings.