What happened
On March 7, 2022, a serious runway incursion occurred at Kumamoto Airport involving two aircraft. An Airbus Helicopters AS365N3, registration JA90MT, operated by the Kumamoto Fire Fighting Disaster Prevention Air Corps, was taxiing for a patient transport drill. At the same time, a Textron Aviation 172S, registration JA47UK, operated by Sojo University, was performing touch-and-go training maneuvers on Runway 07.
As the helicopter approached the runway, the air traffic controller instructed the crew to hold short at Taxiway T6. However, due to radio interference from a passing Boeing 737-800, the helicopter pilot was unable to hear the full scope of updated instructions regarding a change in the takeoff sequence. Misinterpreting the controller's previous communication, the pilot of JA90MT believed they were cleared to proceed. The helicopter entered the runway and stopped within the active area. This movement forced the approaching Textron Aviation 172S to execute an immediate go-around to avoid a collision.
The investigation
The Japan Transport Safety Board (JTSB) examined cockpit voice and flight data recorders, air traffic control communications, and radar tracks. The investigation focused on the sequence of radio transmissions and the crew's interpretation of ATC phraseology. Investigators analyzed the roles of the pilot in command (PIC) and the first officer (FO) during the taxiing phase, as well as the timing of the controller's instructions amidst heavy traffic involving multiple training aircraft and a commercial flight.
Findings
- The primary cause was that JA90MT entered the runway despite being instructed to hold short.
- The pilot's error was driven by a false assumption regarding ATC instructions, stemming from an inability to hear a complete transmission due to a simultaneous transmission from another aircraft.
- The crew failed to correct an erroneous recognition of the instructions.
- The FO did not proactively monitor the situation or challenge the PIC's decision to enter the runway, despite the instruction to hold short.
- The air traffic controller's attempt to update the takeoff sequence was interrupted by the arrival of a Boeing 737-800, leading to a communication gap.