Gulf B789 near Dubai on Mar 10th 2023, tuning control panel malfunction

Last Update: July 18, 2025 / 11:04:50 GMT/Zulu time

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Photo of Gulf Air A9C-FG, Boeing 787-9 Dreamliner — Gulf Air A9C-FG, Boeing 787-9 Dreamliner (Photo credit: Ian A Gratton / Flickr / License: CC by)

Incident Facts

Date of incident
Mar 10, 2023

Classification
Report

Airline
Gulf Air

Flight number
GF-504

Departure
Bahrain, Bahrain

Destination
Dubai, United Arab Emirates

Aircraft Registration
A9C-FG

Aircraft Type
Boeing 787-9 Dreamliner

ICAO Type Designator
B789

A Gulf Air Boeing 787-9, registration A9C-FG performing flight GF-504 from Bahrain (Bahrain) to Dubai (United Arab Emirates), was descending towards Dubai when the crew experienced the failure of the left, center and right tuning control panels followed by EICAS messages indicating the loss of transponder, TCAS and weather radar. The crew was able to communicate with Dubai ATC via their standby radio and was cleared to descend to 13000 feet and enter a hold while troubleshooting. The crew subsequently declared loss of communication and proceeded to land on Dubai's runway 12L.

The UAE GCAA released their summary report concluding the probable causes of the serious incident were:

The Air Accident Investigation Sector could not determine the technical reason behind the malfunction of the three TCPs.

The crew was unable to restore the TCPs because the Copilot, acting as the PM, could not locate the information pertinent to resetting the inoperative TCP as outlined in the electronic flight crew operations bulletin stored in the electronic flight bag.

The non-adherence to the applicable take-off briefing procedure to check the current bulletins and NOTAM supplement, and their lack of knowledge in locating the relevant flight crew operations bulletins hindered the crew’s ability to find the necessary information.

The GCAA analysed:

Risk Analysis of Inoperative TCP

On a Boeing 787 aircraft, the inoperative TCP can pose several risks that need to be carefully managed. The TCP is a critical component in the flight communication and navigation systems, and its failure can affect several aspects of the aircraft's operations such are TCAS, Transponder and Weather radar.

If TCP fails, affecting the operation of radio and navigation systems, the potential risk that impact operations as the TCAS, transponder, and weather radar are non-functional:

TCAS:

Potential Risks:

Inability to Tune Frequencies: If the TCP failure affects the ability to tune frequencies, it could hinder communication with ATC, which may impact TCAS operation indirectly if it involves frequency adjustments for alerts or coordination.

Communication Issues: Though TCAS itself is not directly dependent on the TCP for its core functionality, any associated communication issues might affect how effectively the system is used or monitored by the crew. The TCP may also be used to adjust the sensitivity or mode of the TCAS, such as selecting between "Traffic" and "Resolution Advisory" modes.

Transponder:

Potential Risks:

Frequency Tuning Problems: The TCP is used to tune communication frequencies, including those used by the transponder. If the TCP failure affects frequency tuning, the aircraft may face issues with setting or communicating on the correct transponder frequency.

Invisibility to ATC: An inoperative transponder due to TCP failure could lead to loss of radar contact with ATC, increasing collision risk.

Weather Radar:

Potential Risks:

Radar control issues: The TCP controls various aspects of the weather radar system, including tuning and operation. A failure might prevent the crew from adjusting radar settings or viewing weather information accurately.

Reduced Weather Awareness: Without proper radar operation, pilots may struggle to detect and avoid severe weather conditions, increasing the risk of encountering turbulence or storms.

In conclusion, the Investigation affirms the failure of the TCP affects the ability to tune and operate critical communication and navigation systems.

The indirect risks to TCAS, transponder, and weather radar include:

TCAS: Potential communication issues affecting the usage and monitoring of TCAS alerts.

Transponder: Problems with frequency tuning could lead to invisibility to ATC and communication challenges.

Weather Radar: Difficulty in tuning and controlling the weather radar system, which impacts weather detection and avoidance.

Aircraft Airworthiness

The Aircraft maintenance records did not indicate deferred defects related to the serviceability of onboard navigation systems, and the Aircraft was released to the flight without reported defects.

Crew Performance

Both flight crewmembers were qualified and fit for the flight as per the regulatory requirements.

The flight crew contacted Dubai Approach at 1754:10 reporting the TCP failure and they were unable to change the frequency. The crew was able to communicate on standby radio frequency 119.3 MHz. Dubai Approach controller coordinated with crew for the decent clearance to VETUB3A waypoint.

At the same time, the PM initiated the QRH non-normal checklist and attempted to locate the electronic FCOM in the electronic flight bag (EFB).

The PM stated that he was unable to find any pertinent details regarding the inoperative TCP reset procedure in the FCOM, nor could he find the flight crew operations bulletin for the TCP inoperative reset procedure.

At 18:01:02, the Aircraft was holding at waypoint VETUB while the crew coordinated with Dubai Approach for vectoring and a descent to 13,000 feet.

As per the statement of the Commander, who was acting as the PF, he and the Copilot the multipole attempts to reset and restore the TCP were unsuccessful.

The crew declared radio communication emergency at 1822:15 upon which Dubai Approach controller declared emergency and provided landing clearance runway 12L to the crew. The Aircraft landed safely at 1835:33 on runway 12L.

The Investigation concludes that if the crew have followed the take-off briefing and checked that there is an existing relevant flight crew operations bulletin, number GUL-38 R1, that the crew were unable to identify its location in the electronic copy of FCOM installed on iPad that was placed in EFB.

If crew would have located the bulletin and followed the procedures to reset the inoperative TCP they would have recovered the communication to normal. Due to failure in communication system the PF or PM was unable to contact company Maintenance Control Center (MCC) to resolve the TCP issue.

The Investigation concludes that the crew were unable to locate the relevant bulletin to reset the inoperative TCP as they may not have checked the existing bulletins as per the procedures.

The Aircraft Maintenance performed a reset to all three TCPs and the TCPs were functional and ground test was conducted with no further failures reported. The EICAS messages were cleared.