What happened
On March 18, 2018, at approximately 18:42 JST, an Airbus A320-214, registered B8236, operated by Juneyao Airlines Co., Ltd., entered Runway 18 at Naha Airport and began its takeoff roll without receiving official takeoff clearance. At the time, a Dassault-Breguet Mystère Falcon 900, registered JA8570, belonging to the Japan Coast Guard, was still in the process of vacating the runway via Taxiway W6 after having landed earlier.
The crew of the Airbus A320-214 had been instructed to line up and wait on the runway. During the sequence, the air traffic controller issued instructions to the crew regarding the cancellation of an altitude restriction. Following this transmission, the pilot in command increased engine thrust and released the brakes. Although the tower controller noticed the unauthorized movement and issued urgent commands to stop immediately, the flight crew did not respond to the instruction and continued the takeoff roll. The danger subsided only once the Japan Coast Guard aircraft had fully cleared the runway.
The investigation
The Japan Transport Safety Board (JTSB) examined air traffic control communications, airport surface detection equipment (ASDE) records, and the aircraft's quick access recorder (QAR). The investigation focused on the sequence of communications between the tower and the Airbus A320-214, the positioning of both aircraft, and the cockpit procedures used by the three-person crew. The investigation also looked into the physical layout of the cockpit, noting that the second officer was seated in an observer seat in the rear of the cockpit for training purposes, which limited visual contact with the other pilots.
Findings
- The pilot in command of the Airbus A320-214 made a hasty judgment that takeoff clearance would be issued immediately following the altitude restriction update, leading him to initiate the takeoff roll prematurely.
- There was no record of an actual takeoff clearance being issued or read back by the crew.
- The second officer, acting as the communications trainee, likely misinterpreted the altitude restriction instructions as takeoff clearance or provided an inaccurate read-back.
- The flight crew failed to hear the controller's emergency instruction to stop, potentially because they were focused on the preceding altitude instruction and did not recognize the subsequent callout addressed to them.
- The physical separation between the two aircraft was approximately 1,330 meters at the moment the takeoff roll began.