Five passengers died and the pilot was seriously injured when two aircrafts collided at Haneda Airport on the evening of January 2 earlier this year.

One of the planes belonged to the Japan Coast Guard and was on a mission to transport aid supplies to the Noto Peninsula that was struck by an earthquake the day before.

The Japan Transport Safety Board unveiled a voice recording from the JCG aircraft on December 25 for the first time.

The JCG aircraft’s co-pilot recited “number one,” which means that the aircraft was the first to take off, and the instruction to “drive to the front of the runway” which he received from the air traffic controller. However, the captain only recited “number one” and “C5.” The recording also revealed that he said “there is no issue” before approaching the runway, indicating neither the captain or the co-pilot were aware that they were entering the runway erroneously.

The captain understood that he was instructed to have the aircraft to stand by on the runway. He also explained that the JCG aircraft was given prioritized takeoff in order to transport relief supplies.

The Japan Transport Safety Board will continue to analyze why the JCG aircraft pilots had the mistaken belief that they had been given permission to enter the runway.

Furthermore, the system that alerts air traffic controllers in the event of an unauthorized entry to the runway was activated for 1 minute and 8 seconds, 7 seconds after the JCG aircraft began entering the runway until immediately after the collision. However, air traffic controllers were unaware.

The Japan Transport Safety Board sees the accident as a result of multiple factors.