The Überlingen Air Disaster

On one serene summer night in the year 2002, the lives of 71 people were changed forever when their planes collided dramatically over a small town in Southern Germany. The subsequent investigation to find the reason how two modern aircraft ended up colliding at the same spot, at the same time, uncovered a series of seemingly small factors that combined to cause a devastating air disaster. This story also tells the tale of a father, grieving over the unfortunate loss of his entire family, and his vengeful desires to exert revenge against who he believed murdered them.

Just before 11pm on the 1st of July 2002, BAL Bashkirian Airlines Flight 2937 departed Moscow, Russia, on its way to Barcelona, Spain. The plane was a 7-year-old Russian designed Tupolev Tu-154M, registration code RA-85816, and the charter flight carried 60 passengers and 9 crew members. Some 45 of those passengers were Russian schoolchildren and teenagers from the city of Ufa, in Bashkortostan, Russia. They were the city’s finest prodigies, talented in academics, sports, and the arts. As a reward and as a chance to relax and unwind, the city’s local UNESCO committee had organised a two-week school trip for the schoolchildren, to the Costa Daurada beach area of Catalonia, Barcelona. Flight 2937 was not their original flight, however. The school children left on a train from Ufa to Moscow, but they were unfortunately taken to the wrong airport, and missed their original flight. The organisers took two days to charter Flight 2937 as a replacement flight, giving the children a chance to sightsee around Moscow before leaving for Barcelona that night. The other passengers, who were not involved in the field trip, included the wife and two children of Vitaly Kaloyev, a Russian architect who was waiting for his family in Barcelona.

(RA-85816, the Tu-154 involved in the accident)

The captain of the flight was Captain Alexander Mikhailovich Gross, with the first officer, Oleg Pavlovich Grigoriev, flight navigator, Sergei Gennadyevich Kharlov, flight engineer, Oleg Irikovich Valeev, and an off-duty officer, Murat Akhatovich Itkulov, in the cockpit with him. The first officer of the flight was actually the supervisor of the captain, and today was to be Captain Gross’s assessment flight. Itkulov was normally the first officer for this flight, but his position was taken over for the day by Grigoriev for the purposes of the assessment flight. All of the officers were highly capable pilots, and had collectively logged in over 45,600 flight hours, with an average of 4,807 flight hours each on the Tu-154 aircraft. Flight 2937 was expected to be a smooth ride.

Meanwhile, in Italy, at 11:06pm, DHL International Aviation ME Flight 611 left Bergamo, Italy, heading to the city of Brussels, Belgium. On board the 12-year-old Boeing 757-23APF cargo plane, bearing the registration code A9C-DHL, were two pilots based in Bahrain — British captain Paul Phillips, who had logged in 12,000 flight hours (4,145 of which were on the 757), and Canadian first officer Brant Campioni, who had logged in 6,600 flight hours (176 of which were on the 757). DHL’s Boeing 757 fleet was relatively new to first officer Campioni, but otherwise, Flight 611 was a routine flight for the pilots, and it ran as part of DHL’s worldwide cargo service.

A9C-DHL, the Boeing 757-23APF involved in the accident)

The first seeds of the accident were planted at Skyguide, an air traffic control centre in Switzerland, largely responsible for controlling Swiss airspace, as well as German airspace near the Germany-Switzerland border. At 7:50pm, the night shift air traffic controllers reported for duty, including Peter Nielson, who had 8 years of air traffic controller (ATC) experience. Typically, there would be two controllers on duty during the night shift. However, the other controller on duty was resting in another room for the night, leaving the task of controlling the airspace soon to be entered by both aircrafts solely in the hands of Peter Nielson. This was against company policy, but it had been a common practice for quite some time which was both known and tolerated by the management.

At 11:10pm, technicians arrived in the ATC offices to inform Nielson that the Skyguide management had given them the authority to run routine maintenance on the main radar, causing it to run in “fallback mode”. This was disadvantageous for Nielson, as during the maintenance, the screens would refresh much more slowly, and there would not be a standard visual two-minute proximity warning if planes are too close to each other, known as the short time collision alert system, which Nielson was not made aware of. Soon after, the technicians also shut down the telephone system for repairs, switching over Nielson’s telephone line to the standby telephone line. The timing of the maintenance would come to play a part in what happens next.

The last German controller in contact with Flight 2937 hands them over to Skyguide, before they are due to cross the German border into Switzerland, at flight level 360, or 36,000 feet. Meanwhile, Flight 611 ascends over the Alps, crossing into Swiss airspace at 32,000 feet. Flight 611 then contacts Skyguide to request a climb to 36,000 feet. Nielson grants this request, not realising that Flight 611 was flying at the same altitude. Both planes are now flying at the same altitude, but since they were still quite a distance from each other, they were not in imminent danger, and there was still plenty of time to rectify the issue.

Shortly after, Nielson’s assistant gives him a new flight strip, which informs him of a new flight entering Skyguide’s control, Aero Lloyd Flight 1135, which was flying to Friedrichshafen Airport in Germany. This increases Nielson’s workload dramatically, as he has to manage two  screens at once in order to manage and keep track of all the flights. He called the air traffic control tower in Friedrichshafen in order to hand over Flight 1135 to them, but the phones were not working. Now forced to deal with Flight 2937, Flight 611, Flight 1135, and another flight, Thai Airways Flight 633, he was becoming severely distracted.

While Nielson is distracted with Aero Lloyd Flight 1135, which was on approach to land in Friedrichshafen, a controller in a nearby German air control tower notices Flight 2937 and Flight 611’s collision course, as the visual warning went off, which represents vital information that Nielson was unable to obtain. He tries to contact Nielson, but the phone is unable to get through to Skyguide. He is unable to talk to the pilots directly, due to international air traffic control rules. Soon, Flight 2937 sees Flight 611 on the plane’s TCAS, short for traffic collision avoidance system. It’s a system that is equipped on virtually every plane, in order to prevent air collisions by warning pilots about imminent collisions and directing them to a lower altitude. Flight 2937’s TCAS soon warns Flight 2937 that Flight 611 is getting too close, while at the same time, Flight 611’s TCAS begins to detect Flight 2937. 

TCAS warns Flight 2937 to climb, and Flight 611 to descend. TCAS is effective because the TCAS from two planes can communicate with each other, and work to direct the pilots of both flights to climb or descend correspondingly. However, around this time, Nielson had suddenly realised the two flights were on a collision course, and frantically warned Flight 2937 to descend. Nielson would have no idea what the TCAS was telling the pilots, and so the pilots would have to decide on whether to obey TCAS or the ATC. Nowadays, pilots are trained to always follow TCAS, but back in 2002, it was not set in stone whether the TCAS or ATC instructions were to be preferred. Pilots from the West tended to prefer to follow TCAS, while pilots from the East were more inclined to follow the ATC, assuming that the ATC would know better as the controller of the airspace. In this instance, Flight 611 obeyed the TCAS, while Flight 2937 chose to obey the ATC. Had both flights obeyed TCAS, they would have averted what happened next.

Flight 611 tries to warn Nielson that they have a TCAS warning to descend, but they cannot reach Nielson. Now with 80 seconds to go before the collision was imminent, Flight 2937 realised their actual position when they gained visual sight of Flight 611. In response, Flight 611 increased their descent rate. With two seconds to go, Flight 2937 tried desperately to climb, but it was already too late. At 11:35pm, both planes collided at almost a right angle, at an altitude of 34,890 feet. The vertical stabiliser (or known as the “tail”) of the 757 tears the body of the Tu-154 in half. The pilots of Flight 2937 lose consciousness before hitting the ground due to the sudden decompression and loss of oxygen. Flight 611 struggles for around 7 more kilometres before crashing in the woods near the village of Kaisersdorf, at a 70-degree downward angle. Its engines ended up several hundred metres away from the main wreckage, suggesting that it was broken off mid-air, due to the stress of the plane diving to earth. Both wreckages had collided and fallen over the city of Uberlingen, a southern German town on Lake Constance, near the German-Swiss border; the debris spread over 336 square kilometres. All 71 people on board both planes are dead. It is the worst air collision in post-war German history.

(Part of the wreckage of Flight 2937)

Days after the accident, the first relatives of the dead begin to arrive, including Vitaly Kaloyev. While visiting the crash site, he manages to find his 4-year old’s daughter’s broken necklace in the forest. Sometime later, he finds his daughter’s body intact. His wife and his son were later found in a mutilated state. More relatives arrived, six days after the crash. They were not permitted to see the bodies of their loved ones, as most had been badly charred and mutilated. 53 of the passengers on Flight 2937 were buried in the Ufa Southern Cemetery, a commemorative cemetery remembering the memory of the prodigies on board that day. Vitaly Kaloyev designed a big monument to be placed in another cemetery in his family’s memory. He frequently visited his family’s grave and mourned severely.

(The memorial Vitaly Kaloyev built of his family)

In the aftermath of the disaster, at Skyguide, ATC was run at a reduced capacity for approximately three weeks, due to a lack of available controllers. Peter Nielson never worked as an ATC again, due to the huge mental toll the accident had on him. The media looked for a scapegoat to blame for the accident. They initially blamed the Russian pilots, under the perception that they could not understand English well, and that they had disobeyed their TCAS, which went against aviation standards. However, as more details came forward, the media began to target Peter Nielson, for leading the two planes to the same altitude. Other controllers at Skyguide were repeatedly chased by the media in order to inquire about Peter Nielson. Nielson was put on full blast by the media, and he effectively went into hiding.

The accident was investigated by the German Federal Bureau of Aircraft Accident Investigation (BFU), and they concluded that the factors that caused the incident were due to Peter Nielson’s delay in noticing the mistake he made before the crash, and that the Russian pilots were wrong to obey the ATC instead of TCAS. Their report also heavily criticised Skyguide for allowing a singular ATC to manage the entire Swiss airspace. After the accident, Skyguide promised to make key changes in their operations, and they still manage Swiss airspace to this day.

In July of 2003, many parents, including Vitaly Kaloyev returned to the crash site for the 1-year anniversary of the crash. A memorial was built around the crash site, metal balls symbolising pearls, and a broken necklace. Among the people who attended the 1-year anniversary of the crash was the head of Skyguide. During the ceremony, he was approached by Vitaly Kaloyev, and he was asked about who was on duty that night. The head of Skyguide refused to answer Kaloyev, in order to protect Nielson’s privacy. However, this only fueled Kaloyev’s lust for vengeance, as he became a broken man over time, desperate to find the “killer” of his family.

On the 24th of February 2004, Vitaly Kaloyev showed up at Peter Nielson’s house in Kloten, near Zurich. After confronting Nielson, in anger, Kaloyev stabbed and killed Peter Nielson at his doorstep. Kaloyev fled the scene but was soon discovered at a nearby motel by police. He was sentenced to 8 years in prison for manslaughter, but his sentence was later reduced by a Swiss judge, who ruled that his mental state was not assessed during his trial. After being released in November of 2007, he returned to his hometown, where he was treated as a hero, and expressed no regret for his actions. 

For the families of the dead schoolchildren though, they never wanted Nielson to be killed, instead wanting Skyguide to take major responsibility for the crash. They did not want to add more victims to their suffering, because of their children. As one parent put it, “my life did not change, it stopped”. That is the reality that the parents of these children have to face, due to the mishaps that led to one of the most devastating air disasters in recent memory.

(The Ufa Southern Cemetery, where 56 of the passengers are buried)

At Skyguide, Peter Nielson is remembered by a single white rose, which sits at his former desk to this day.

By: Haikal Danial

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