WASHINGTON and SINGAPORE—The Japan Coast Guard De Havilland Canada Dash 8 struck by an arriving Japan Airlines (JAL) Airbus A350 at Tokyo International Airport Jan. 3 was on the runway despite air traffic control (ATC) instructions to hold short on an intersecting taxiway—directions that one of the Dash 8 pilots read back correctly, a transcript released by Japan’s Ministry of Land, Infrastructure, Transport and Tourism (MLIT) shows.

“Tower, JA722A C,” someone from the Japan Coast Guard (JCG) Dash 8-300 radioed to Tokyo Haneda (HND) tower ATC, indicating the aircraft is checking in from Taxiway C with its tail number as a call sign, according to the transcript.

“JA722A, Tokyo tower good evening,” a controller responded. “Number one, taxi to holding point C5.”

The “number one” suggests the aircraft is next in line to depart. The rest is clear: Move to the marked stopping point on taxiway C5, which connects to HND’s Runway 34 Right (34R).

“Taxi to holding point C5 JA722A, number one, thank you,” someone on the JCG Dash 8 said.

But instead of stopping at the hold-short line on C5, the Dash 8 taxied onto the runway.

Ten seconds before the exchange began, ATC cleared JAL Flight 516 (JAL516), the inbound A350-900, to land on 34R.

Surveillance video shows the Dash 8 moved onto 34R and stopped—something a pilot would do if executing a “line up and wait” ATC command that gives an aircraft permission to enter the runway but not depart.

Nearly 50 sec. after the Dash 8 stopped, the A350, which touched down seconds before closer to the runway end, struck the national guard aircraft. Five of the six Dash 8 occupants died, while all 379 onboard JAL516 evacuated safely once the widebody came to rest.

According to a transcript excerpt released by MLIT, JAL516 contacted Tokyo Tower at 5:43:02 p.m. local time, and was instructed by tower controller to continue its approach to runway 34R. JAL516, first in line to land, read back ATC’s instructions.

JAL516 was then cleared to land at 5:44:56 p.m. and a pilot read back the instructions.

At 5:45:11 p.m., JA722A called into tower frequency notifying of its position on taxiway C. ATC gave the instructions to proceed to the C5 hold line, which JA722A confirmed eight seconds later.

Communications from several other aircraft are detailed in the transcript excerpt, including departing Delta Air Lines and JAL flights told to hold short at C1 as well as another arriving JAL flight.

The transcript ends before the collision. A JAL statement puts JAL516’s arrival time at 5:47 p.m.

The exchange suggests how ATC instructions were given and followed will be one of the key focus areas for investigators as they work to piece together the accident’s chain of events.

Also of interest will be the status and condition of airfield lighting and safety aids. A Notice to Air Missions (NOTAM) issued Dec. 27, 2023, and effective through late February lists several airfield aids at HND as out of service. Among them: lights that illuminate stop bars along the connections between Taxiway C to the accident runway, including C5. Runway 34L centerline lights were also listed as inoperative. It is not clear if the C5 stop bar lights or centerline lights were working at the time of the accident.

Investigators will also look closely at how an aircraft could be on an active HND runway for nearly 1 min. without being detected, even in the dark. An ICAO document shows HND is one of many airports that uses surface movement radar—a long-used method of supplementing the visual view of the airfield controllers have. The system’s performance and controllers’ familiarity with it are other likely topics investigators will probe.

The Japan Safety Transport Board (JTSB) is leading the accident investigation with assistance from several organizations, including Airbus and investigators from France’s Bureau of Enquiry and Analysis for Civil Aviation Safety (BEA). JTSB has recovered the Dash 8 cockpit voice recorder.

The accident caused the cancellation of 137 domestic and four international flights from HND on Jan. 3, MLIT said.