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2002 Überlingen mid-air collision

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2002 Überlingen mid-air collision
Occurrence
Date1 July 2002
SummaryMid-air collision
SiteÜberlingen, Germany
Fatalities71
Injuries0 (all dead)

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|- Template:End frame Bashkirian Airlines Flight 2937 was a Russian aircraft which collided with a DHL-owned cargo plane, on July 1, 2002 at 21:35 (UTC), near the German town of Überlingen, near Lake Constance.

The flights involved

The Bashkirian Airlines plane was a Tupolev 154, travelling from Moscow to Barcelona carrying 57 passengers and 12 crew. Fifty-two of the passengers were Russian children whose school had won them a trip to Spain.

The DHL plane was a Boeing 757 travelling from Bergamo, Italy to Brussels with two crewmembers aboard.

The accident itself

The two planes were flying at 36,000 feet, on a collision course. The air space, even though it lies in Germany, was controlled from Zürich by the private Swiss airspace control company Skyguide.

The air-traffic controller was working two work stations at the same time and was late to realise the danger facing the two planes. However, less than a minute before the crash he did contact the Russian plane, instructing the pilot to descend by 1,000 feet to avoid collision with crossing traffic (i.e., the DHL Boeing). Seconds after the Russian crew initiated the descent, their TCAS collision avoidance system instructed them to climb, while at about the same time the TCAS on the DHL flight instructed that pilot to descend. Had both planes followed those instructions, it is unlikely that the collision would have occurred. The DHL pilot followed the TCAS instructions and initiated a descent, but could not immediately inform the air-traffic controller about this, due to the fact that the air-traffic controller was dealing with the Bashkirian plane. The Russian pilot did not, however, follow the TCAS instruction and continued to descend, as instructed by the air-traffic controller.

Unaware of the TCAS-issued alerts, the air-traffic controller at Zürich repeated his instruction to the Russian plane to descend, giving the crew incorrect information as to the position of the other plane, due to the fact that maintenance work was being carried out on the primary radar, and had to use a slower system. Precious seconds were lost as the Tupolev crew tried to locate the DHL flight visually in the dark, all the time following the ground control orders instead of those given by the collision avoidance system. Thus, both planes descended.

The results were fatal. The planes collided at a right angle, with the DHL aircraft's vertical stabilizer slicing through the Tu-154's fuselage. The Tupolev promptly exploded and broke into two, while the 757 struggled for a further 7 kilometres before crashing near a mountainside, one engine parted explosively before it hit the ground. All 71 people aboard both planes were killed.

Other factors in the crash

Only a single air-traffic controller, Peter Nielsen of ACC Zürich, was controlling the airspace the planes were in. The only other controller on duty was resting in another room for the night. This was against the regulations, but had been a common practice for years and was known and tolerated by the management.

In addition, a ground based collision warning system, which would have alerted the controller to imminent collisions early, had been switched off for maintenance (of which the controller was unaware of the extent at the time). Phone lines at Skyguide were down, also as part of maintenance work, which also prevented adjacent air-traffic controllers at Karlsruhe from phoning in a warning.

In the minutes before the accident, Nielsen was occupied with a delayed flight approaching Friedrichshafen airport. He had to handle two workstations at once, and was struggling with the malfunctioning phone system. Due to these distractions he did not spot the danger until about a minute before impact. Had he ordered the Russian plane to descend earlier, the collision avoidance systems would never have issued any instructions. When he realized that the situation (the multiple factors in two workstations) was overwhelming, it was too late to summon assistance.

Finally, the Bashkirian crew was delayed in getting vital instructions from Nielsen, as their transmission calling for instructions on how to avoid the DHL plane was blocked by the Skyguide transmission to the cargo plane. In essence, while Nielsen was speaking to the DHL flight, the early calls for assistance from the Russian crew could not be received by the controller. This caused a 23-second delay in Nielsen's response to the commercial flight, which could also have made a difference in avoiding the collision.

Many believe that this accident could have been avoided if the proper lessons had been taken from a "near-miss" which occurred about a year before the Bashkirian-DHL collision. Two Japanese airliners, both Japan Air, nearly hit each other in Japanese skies. The two planes were on a collision course, and the pilots of both planes were getting conflicting instructions from their TCAS units and the flight controller. Disaster was avoided because, by sheer chance, both pilots, each unaware of the other's decisions, followed the TCAS instructions, ignoring the controller's orders. Even so, they missed each other by less than 100 meters, and the abrupt maneuvers that were necessary to avert disaster left about a hundred passengers hurt, a few of them suffering severe injuries. Japanese authorities called for measures that would prevent similar accidents from happening, but they were ignored.

Peter Nielsen was stabbed to death in front of his home in Zürich on February 24, 2004. A Russian man, Vitaly Kaloyev, was arrested within a few days. Kaloyev had lost his wife and both of his children, who were aboard Bashkirian Airlines 2937. He is reported to have suffered a nervous breakdown following the loss of his entire family, especially since he was one of the first relatives to arrive at the crash site. Kaloyev participated in the search for the bodies and, tragically enough, located his own daughter's body, which was surprisingly intact (unlike his wife's and son's, which were found only days later, mutilated). Kaloyev spent the first year after the accident lingering at the graves of his family, and on the memorial service for the first anniversary of the tragedy, in 2003, he asked the head of Skyguide about the possibility of meeting the controller who had been responsible for the disaster. He was ignored. After travelling to Zürich and stabbing Nielsen, Kaloyev was found in his hotel room, apparently in shock. He claimed having no memory of what he had done, and was taken to a mental hospital, where he was to be evaluated in order to determine if he is fit to stand trial. He remains incarcerated in Switzerland. On October 26 2005 he was sentenced to eight years of prison. Taking into account his 610 days incarceration before the sentence he should be freed in 2011.

Nielsen's death is made even more tragic by the fact that in truth managerial incompetence and systems failures were really to blame for the accident. As explained above, a series of coincidences played a key role for the accident to happen, but Kaloyev was unaware of the circumstances leading to the accident. Experts have argued that, given the malfunctioning phone system, inadequate staffing levels and the co-occurrence of the problem in Friedrichshafen, Nielsen could not even be blamed for the disaster. He could have prevented it, had he been fortunate enough to notice the risk of collision sooner, but since he did not, many factors made it nearly impossible for Nielsen, or anyone who had been there, to prevent the accident. In fact, Nielsen had retired from his job as controller, since he had been struck by grief and guilt over the incident. At Skyguide, his former colleagues maintain, to this day, a vase with a white rose over Nielsen's workstation.

On May 19, 2004, the German federal aviation accident investigative office BFU made the results of their inquiry into the crash public. Skyguide, after initially having blamed the Russian pilot for the accident, accepted responsibility and has paid compensation to some of the Russian families. A criminal investigation of the Skyguide actions is ongoing as of May 2004.

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