With a 'runway incursion system' - https://www.atgairports.com/solutions-and-systems/airfield-control-systems/runway-incursion-systems https://www.atgairports.c

With a 'runway incursion system' - https://www.atgairports.com/solutions-and-systems/airfield-control-systems/runway-incursion-systems https://www.atgairports.com/solutions-and-systems/airfield-c... You don't necessarily need a system that scales all the way down to tiny airports. Major airports like Haneda presumably already have things like stop-bar lighting, for operating in foggy weather. If we already know where each aircraft is, and whether they're permitted to cross the stop bar right now - I can believe this runway incursion could have been detected.