NHK has learned that the crew onboard a Japan Coast Guard plane that fatally collided with a passenger jet at Tokyo's Haneda Airport in January may have been distracted immediately before the accident.

The collision occurred on January 2 in which the Coast Guard plane on a runway was hit by a Japan Airlines passenger plane that had just landed.

The Coast Guard aircraft was about to take off on a mission to deliver relief goods to an airbase in Niigata Prefecture for survivors of a major earthquake that struck the Noto Peninsula on New Year's Day.

Both aircraft burst into flames. Five Coast Guard crewmembers died in the accident.

All people onboard the JAL passenger jet were evacuated, although more than a dozen passengers later received medical treatment.

Before the collision, air traffic controllers gave the Coast Guard plane an instruction of "number one" that indicates the order in which planes should take off at Japanese airports.

The crew on the Coast Guard plane are believed to have mistakenly entered the runway after its pilot possibly misinterpreted "number one" as clearance for takeoff.

The Japanese government's Transport Safety Board has analyzed data of voice recorders recovered from the plane.

Sources say that the safety board has found the Coast Guard plane crew members continued their conversation on their mission for quake-hit areas until just before the collision.

In addition to communications with air traffic controllers, the crew communicated with the Coast Guard airbase at Haneda.

The government board intends to further investigate factors that led to the accident, including a possibility that the crew did not give their full attention to the take-off procedures.

It is also believed both the air traffic controllers and the JAL jetliner pilots failed to notice that the Coast Guard plane had entered the runway.

The safety board plans to release soon an interim report on its investigation.