What happened
On the early morning of July 20, 2023, a Boeing 737-80 and registration B-5156, operated by China Postal Airlines LLC, was on an approach to Kansai International Airport. At the time, two inspection vehicles were active on the airfield. Vehicle B was performing a scheduled inspection of Runway 06L/24R.
During the approach, the ground controller received a radio report from Vehicle A, which was inspecting a different runway (Runway 06R/24L). The ground controller mistakenly believed this report—stating that the vehicle had vacated the runway—referred to Vehicle B. Consequently, the ground controller informed the tower that the runway was clear. Relying on this incorrect information and unable to visually confirm the vehicle's position, the tower controller issued a landing clearance to the arriving aircraft while Vehicle B was still traversing the runway.
The aircraft continued its approach and landed at 05:35:53 JST. The driver of Vehicle B, noticing the approaching aircraft, accelerated to vacate the runway via Taxiway B10. The closest distance between the aircraft and the vehicle was approximately 3,480 meters before the runway was cleared.
The investigation
The Japan Transport Safety Board (JTSB) examined ATC communications, radar tracks, and the drive recorder from Vehicle B. The investigation focused on the sequence of radio transmissions and the controllers' visual monitoring of the airfield. The investigators also reviewed the operational environment, noting that the ground controller was managing high-pressure tasks, including coordinating scheduled firefighting and rescue exercises and managing recent navigation aid failures caused by lightning strikes.
Findings
- The primary cause was the tower controller issuing a landing clearance to the Boeing 737-800 while Vehicle B was still occupying the runway.
- This occurred because the tower received incorrect information from the ground controller, who had misidentified a radio report from Vehicle A as being from Vehicle B.
- The ground controller's error was driven by a reflexive response to the word "operation" in the radio call, leading them to believe the message concerned the active inspection vehicle on Runway B.
- The tower controller failed to visually confirm that Vehicle B had actually exited the runway before authorizing the landing.
- High levels of psychological pressure and stress on the ground controller, stemming from the need to coordinate complex rescue exercises and manage technical navigation issues, contributed to the communication error.