The burnt-out wreckage of a Japan Airlines plane at Tokyo’s Haneda airport was a sobering reminder that many of aviation’s worst accidents happen on the ground rather than in the air.

Safety investigators spent the week probing the sequence of events that led to a collision between the JAL Airbus A350 and a smaller coastguard turboprop aircraft as the former landed on the runway. All of the nearly 400 passengers and crew on board escaped the JAL plane, but five of the six-member coastguard team were killed.

Japan Transport Safety Board’s investigation is running in parallel with a police probe into possible professional negligence. State broadcaster NHK reported on Friday that airport camera footage showed the coastguard plane may have erroneously been on the runway for as much as 40 seconds before the collision.