Investigation Summary
The incident highlighted a critical ambiguity in international aviation regulations regarding the hierarchy of commands between human controllers and automated safety systems. At the Tokyo Area Control Center, a trainee controller, Hideki Hachitani, was managing ten flights simultaneously. When a Short Term Conflict Alert (STCA) appeared on his screen, he intended to tell Flight 958 to descend but mistakenly addressed Flight 907. His supervisor, Yasuko Momii, attempted to intervene but used an incorrect flight number ('Japanair 957'), which resulted in no response from either crew. Onboard the aircraft, the TCAS II (version 6.04a) logic functioned correctly by issuing coordinated, complementary advisories: a climb for the 747 and a descent for the DC-10. However, the 747 crew chose to prioritize the controller's verbal instruction to descend. This created a 'chase' scenario where both aircraft were descending into each other's path. The DC-10 crew, following their TCAS, did not hear the controller's subsequent attempts to turn them because of radio congestion and the intensity of the cockpit alerts. The near-miss occurred with a vertical separation estimated between 20 and 60 meters (66 to 197 feet). The incident is frequently cited alongside the 2002 Uberlingen disaster as the primary catalyst for global changes to TCAS operating procedures.
Final Conclusions
The Aircraft and Railway Accident Investigation Commission (ARAIC) concluded that the air traffic controller's error in issuing instructions to the wrong flight and the Flight 907 pilot's decision to follow ATC instructions instead of the TCAS Resolution Advisory were the two main causes of the accident. The commission noted that at the time, ICAO provisions and Japanese regulations did not explicitly state that TCAS RAs must always take precedence over ATC instructions. The investigation also cited the trainee's lack of experience and the supervisor's failure to provide effective recovery instructions.
Video Analysis
Terror Over Shizouka | 2001 Japan Airlines Mid-Air Incident — A detailed reconstruction of the near-collision between JAL Flight 907 and JAL Flight 958, exploring the ATC errors and the TCAS conflict that nearly led to the deadliest aviation accident in history.
If playback is blocked, the owner has disabled embedding — use the link above.
Airframe & Maintenance
Japan Airlines JAL907 — Boeing 747-446D · JA8904
Systems & Failure Modes
TCAS II
Traffic Collision Avoidance System designed to provide 'Resolution Advisories' to pilots. In this event, the system worked as designed, but its instructions were ignored by one crew in favor of ATC commands.
STCA
Short Term Conflict Alert, a ground-based safety tool that alerts controllers to potential separation violations.
Interesting Facts
- 01The two aircraft passed within approximately 135 meters (443 feet) of each other.
- 02There were 677 people on board the two aircraft combined (427 on the 747, 250 on the DC-10).
- 03The evasive maneuver on Flight 907 was so violent that a drink cart became embedded in the cabin ceiling.
- 04The incident led to a landmark criminal trial in Japan where two air traffic controllers were found guilty of professional negligence.
- 05The TCAS version in use (6.04a) did not support RA reversals in coordinated encounters.
Safety Actions & Advisories
ICAO Regulation Amendment
In November 2003, ICAO amended PANS-OPS (Doc 8168) to explicitly state that pilots must follow TCAS Resolution Advisories even if they conflict with ATC instructions.
TCAS II Version 7.1 Development
The incident contributed to the development of TCAS version 7.1, which introduced improved reversal logic to handle scenarios where one aircraft does not follow its initial advisory.
Known Controversies & Unanswered Questions
Criminalization of ATC Errors
Reference ↗The prosecution of the controllers was highly controversial within the global aviation community, with safety advocates arguing that criminalizing honest mistakes undermines 'Just Culture' and discourages incident reporting.