B747/DC10, Japan Airlines, Suruga Bay Japan, 2001 (Legal Process - Air Traffic Controller)
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Date: 31 January 2001
Location: over the Suruga Bay near the city of Yaizu, Shizuoka Prefecture, Japan
On 31st January 2001, a Boeing 747-400 almost collided midair with a MCDONNELL DOUGLAS DC-10, off the Japanese coast near the city of Yaizu. The avoiding action undertaken by the crew of the B747 prevented the collision; however, it caused 100 injuries on board and damage to the aircraft interior. The near collision occurred after an ATC control lapse had led to a conflict which caused coordinated TCAS RAs. The DC10 followed the RA but the B747 crew, in the presence of a conflicting ATC instruction, did not.
A Boeing 747-400, Japan Airlines Flight 907, with 411 passengers and 16 crew was conducting a domestic flight from Tokyo Haneda International Airport to Naha Airport.
A McDonnell Douglas DC-10-40, Japan Airlines Flight 958, with 237 passengers and 13 crew, was conducting an international flight from Pusan International Airport to Tokyo Narita International Airport.
The B747 had a crew of 2 (Captain and First Officer) and 2 supernumerary co-pilots on the flight deck while the DC10 had a crew of 3 on the flight deck: Captain, First Officer, and Flight Engineer. Both aircraft were equipped with TCAS II version 6.04a. The near collision occurred in VMC daylight conditions.
At the time of the event, three air traffic controllers were on duty at Tokyo ACC at Kanto South C sector: a trainee undergoing on-the-job (OJT) familiarization training on the sector, an instructor who supervised the trainee, and a coordinator.
The B747 made a first contact with Kanto South C sector while passing 11,000 feet climbing to FL390. Approximately 8 minutes later, the DC10 made first radio contact with the same sector reporting maintaining FL370. At this point, the aircraft were on almost parallel tracks.
Approximately 100 seconds prior to the near midair collision, the B747 started to turn left according to its flight plan. As a result of the turn, the aircraft were on converging trajectories. The controllers first became aware about the developing conflict situation 57 seconds prior to the near midair collision when the STCA alert was displayed on their screen and the B747 was passing through FL367 climbing to FL390.
A few seconds after the STCA alert on the ground, both crews received TCAS Traffic Advisories. 12 seconds after receiving the STCA alert, the ATC trainee instructed the B747 to descend to FL350 “due to traffic”. The B747 crew acknowledged the instruction adding that they had traffic in sight. When they were reading the instruction back, TCAS II generated a Climb RA for the B747 requiring a climb with a rate of 1500 ft/min. During the readback of ATC instruction, the TCAS aural annunciation could be heard in the background. The B747 reached FL372 before it started to descend in response to the ATC instruction.
Simultaneously, TCAS issued a Descend RA for the DC10 requiring a descent rate of 1,500ft/min. The DC10 started to descend. Soon after, the ATC trainee instructed the DC10, which was flying on the heading of 095°, to turn right onto a heading of 130°. There was no response from the DC10 crew to this instruction.
Fourteen seconds after the initial RA, TCAS issued a strengthening RA for the DC10 (“Increase descent”), requiring the descent rate of 2500 ft/min. At the same time, the trainee again called the DC10 instructing it to turn right onto a heading of 140°. Again, there was no response from the DC10 crew. Both aircraft were descending towards each other.
Six seconds after the second turn instruction for the DC10, the instructor took the frequency over and instructed “Japanair 957” to commence descent. As there was no aircraft with that callsign, there was no response.
Subsequently, the instructor called the B747 telling them to climb to FL390. The B747 did not respond. Soon after, the RA for the B747 strengthened to “Increase climb” (at 2500 ft/min.); however, the B747 continued to descend.
Approximately 36 seconds after the first RAs were issued, the aircraft passed each other at FL356 with the vertical separation of approximately 130 feet.
In the last moment, based on visual judgement, the DC10 crew increased their descent rate and the B747 pilot pulled up to avoid an imminent collision. The sudden change in the G forces on the B747 caused 100 injuries (including 9 serious), as well as damage to the cabin interior (including a drinks cart being catapulted and embedded in cabin ceiling).
The B747 returned to Haneda, so the injured could be taken care of, while the DC10 continued to Tokyo Narita as planned.
The Non-Judicial Investigations
The (at that time) Aircraft and Railway Accident Investigation Commission (now the Japan Transport Safety Board) investigated the event (which was classified as an accident due to the injuries).
The Commission concluded that the air traffic control's error in giving instructions to the wrong flight and the pilot’s decision to follow air traffic control instructions instead of the TCAS Resolution Advisory (RA) were the two main causes. The Commission has observed that the B747 Captain was not sufficiently aware of the importance of complying with RAs and the danger of opposite responses. The Commission has noted that neither ICAO provisions nor Japanese regulation nor company manuals did mention that pilots must comply with RA even if there was a conflict between the manoeuvre required by the RA and ATC instructions. Furthermore, the Commission concluded that the ICAO provision contained in Doc. 8168 (PANS-OPS) contained a statement giving the pilot full authority in the choice of the best course of action to resolve a traffic conflict.
The Commission has also observed that neither crew reported the RAs to ATC although that was required by the Regulation in force at the time.
The Regulator imposed the following penalties:
- Controller (OJT instructor): Salary cut by 10 percent
- Controller (trainee): Reprimand
- Chief Controller: Reprimand
The Criminal Prosecution
Persons prosecuted: The two controllers (OJT instructor and trainee). The prosecutors did not pursue their case against the Captain of Flight 907 due to lack of evidence.
The first court: Tokyo district court
The Charges: Professional negligence resulting in injury
The Plea: Not guilty
Prosecutors Sentencing Request:
- Controller (OJT instructor): One year and six months imprisonment
- Controller (trainee): one year imprisonment
The verdict: Not Guilty
Prosecutor appeal lodged: 31 March 2006
The second court: Tokyo high court
The verdict: Guilty
- Controller (OJT instructor): One year and six months imprisonment suspended for three years.
- Controller (trainee): one year imprisonment suspended for three years.
The accused appeal lodged to the Supreme Court: 14 April 2008
The third court: The Supreme Court
The verdict: Appeal rejected. The sentence upheld on 26 October 2010. As Japanese government employees cannot have a criminal record, both controllers were terminated.
Changes to ICAO Provisions
The ICAO provisions, contained in ICAO Doc 8168 PANS-OPS, which was in force at the time of the event were found by the investigation not sufficiently clear. In the wake of this accident as well as the 2002 Überlingen midair collision, Doc 8168 provisions were amended to clearly state pilot action in case of RA: “follow the RA even if there is a conflict between the RA and an air traffic control (ATC) instruction to manoeuvre” (3.2.c.2).
Changes to TCAS Logic
Both aircraft involved in the Yaizu accident were equipped with TCAS II version 6.04a. This version did not allow RA reversals in coordinated encounters (i.e. with other TCAS equipped aircraft), so no change of RA sense was possible in this accident. In case of non-compliance by one of the aircraft, like it was in the Yaizu case, TCAS was unable to solve the conflict.
As version 6.04a was not compatible with RVSM operations (which were phased in during the early 2000s), TCAS II version 7.0 was introduced. This version brought not only compatibility with RVSM operations but also an option to issue RA reversals in coordinated encounters. However, the reversals were not allowed if both aircraft were in “100-foot vertical chase” (i.e. descending or climbing simultaneously and remaining within 100 feet of each other) which prevented an RA reversal in the Überlingen midair collision. This issue was addressed in TCAS II version 7.1, which is currently mandated in European airspace and elsewhere.
The case of the Yaizu near-midair collision is frequently cited by the promoters of Just Culture. The prosecution and sentencing of air traffic controllers is seen an example of prosecution that may lead to the decrease of safety issue reporting because of the fear of prosecution, and consequently vital safety information may be concealed.
- Level Bust
- Airborne Collision Avoidance System (ACAS)
- Human Error in Aviation and Legal Process
- Just Culture