JAL A350 collision: Tokyo Haneda runway-conflict system ‘difficult to rely on’

Japanese investigators have indicated that a runway conflict alert was active for over a minute before the fatal collision between a Japan Airlines Airbus A350 and a De Havilland Dash 8 at Tokyo Haneda. But the Japan Transport Safety Board found that controllers in the airport’s east tower felt the system was “difficult to rely on” because it generated nuisance warnings when there was no runway occupancy overlap. The airport’s east side ground controllers also considered the system “insufficient” to support visual situation assessment. As such, controllers “did not normally expect to take any action” even if a warning was displayed, the inquiry states. The system uses position information for ground traffic derived from airport surface detection equipment and multilateration, as well as data on airborne aircraft from surveillance radar. It was introduced at Tokyo in fiscal 2010 and monitors all four runways at Haneda, and its status is displayed at 14 controller stations. The system is designed to detect the presence of a taxiing aircraft which has crossed the holding point of an active runway, at least 48s before an arriving flight is predicted to reach the runway threshold. If such a conflict is detected, the affected runway turns yellow on the monitoring screen, and the corresponding data block of the aircraft involved also changes, visually alerting the controller. At the time of the Haneda accident, on 2 January 2024, the system did not have an audio alarm. According to the inquiry, the system could trigger false alerts because of built-in safety margins in the way it calculates distances using aircraft transponder and multilateration data.<br/>