What happened
On October 27, 2018, at approximately 12:38 JST, a Gulfstream Aerospace G-VI, registered B-3276, operated by Shanghai Deer Jet Co., Ltd., entered Runway 22 at Tokyo International Airport without proper clearance. At the time, a Cessna 510, registered JA123F, operated by Okayama Air Service Co., Ltd., was on final approach to the same runway with landing clearance.
The crew of the B-3276 was taxiing toward Departure Runway 16R and had been instructed to hold short of Runway 22. While attempting to establish communication with the Local North controller, the crew experienced difficulties with their radio transmissions. Although the crew believed they had received confirmation to cross the runway, the air traffic controller had actually been communicating with a different aircraft. Consequently, the B-3276 crossed the active runway, prompting the controller to order the JA123F to execute an immediate go-around. The incident was classified as a serious incident, though the distance between the two aircraft at the time of the incursion provided enough margin to avoid a collision.
The investigation
The Japan Transport Safety Board (JTSB) examined radar track records, air traffic control (ATC) communication logs, and illumination records from the runway visual surveillance system. Investigators also reviewed the Digital Flight Data Recorder (DFDR) from the B-3276 to analyze VHF radio keying patterns.
Key aspects of the investigation included:
- Analyzing the discrepancy between the aircraft's radio transmissions and the ATC records, which showed that several transmissions from the B-3276 never reached the controller.
- Evaluating the effectiveness of the runway visual surveillance system (VMS) and why the crew did not notice the illuminated warning signs.
- Investigating the cause of the communication breakdown, specifically why the crew's attempts to establish contact were not received by the tower.
- Reviewing the cockpit environment, including the impact of radio interference from other aircraft on the crew's ability to hear instructions.
Findings
- The primary cause of the incursion was a communication failure where the crew of the B-3276 misunderstood air traffic control instructions. The crew believed they had received clearance to cross the runway after misinterpreting a fragment of a transmission intended for another aircraft as an "affirm" response.
- A significant contributing factor was that the radio transmissions from the B-3276 to the Local North controller were not being received, meaning a proper sequence of call and reply was never established.
- The flight crew did not notice the illuminated runway visual surveillance system (VMS) warning lights, likely due to a lack of familiarity with the specific operation of the system at Tokyo International Airport.
- While the crew heard only part of the controller's message due to interference from other aircraft, the lack of a verified read-back meant the error went undetected until the aircraft had already entered the runway.