What happened
On August 1, 2015, a Boeing 787-800 was operating in the NAT MNPS airspace. Upon reaching the limit of VHF communication range, air traffic control instructed the crew to establish contact with the next oceanic control sector using HF frequencies. Although the crew could clearly receive transmissions from both other aircraft and ground-based radio stations, they were unable to initiate contact with the controller.
The crew attempted to establish communication using both onboard HF radio units and all available frequencies. To comply with mandatory reporting regulations, the crew successfully relayed their position report to the air traffic control center via another aircraft. Once the aircraft entered the next control sector, the crew managed to establish HF communication using one radio unit, though the second unit remained non-functional. The remainder of the flight proceeded without further communication issues.
The investigation
The investigation focused on the failure of the onboard communication equipment. Following consultations with the aircraft manufacturer, it was determined that the hardware required replacement. The investigation established that the issue was resolved by replacing both HF radio units and the antenna coupler.