This year marked twenty years ago since the Überlingen mid-air collision. On the evening of July 1st, 2002, two planes crashed above the small town of Überlingen in southern Germany, leading to a total of 71 deaths across the two aircraft. Thankfully, there were no casualties on the ground, as the debris largely fell into a woodland area. Let's take a look back at the events concerning the crash.

Introduction

The main cause of the flight was attributed to the air traffic controller working on two workstations at the same time. This meant that he failed to ensure adequate separation between the two aircraft, ultimately leading to the collision. However, confusion regarding prompts issued by the traffic collision avoidance systems (TCAS) of the aircraft involved was also found to have been a contributing factor.

The result of this unfortunate incident was an extensive investigation by the German federal government. This ultimately called for additional training for both pilots and air traffic controllers, in order to prevent such catastrophes from occurring in the future. The two flights involved were rather different in their nature.

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Bashkirian Airlines flight V9-2937

The first aircraft involved in this accident was a Tupolev Tu-154M. According to the Aviation Safety Network, it was registered as RA-85816 and operated by BAL Bashkirian Airlines on flight V9-2937. This was a charter service between Moscow Domodedovo International Airport (DME) and Barcelona El Prat Airport (BCN).

The BAL Bashkirian Airlines service carried many children of high-ranking officials of the Republic of Bashkortostan, a semi-autonomous region in the Russian Federation with its capital located in the city of Ufa. The population of the republic was approximately 4 million, making it one of the ten largest Russian republics.

These Russian schoolchildren were on their way to Catalonia on a school trip organized by the UNESCO committee. The pilots on this service were also very experienced, and there were three qualified pilots, along with a flight navigator and a flight engineer. The reason for the presence of a third pilot in the cockpit was that the airline's chief pilot was evaluating the flight's Captain.

DHL Aviation flight ES-611

The second aircraft was a Boeing 757-23APF operated by DHL International Aviation ME on flight ES 611, a cargo service flying between Manama, Bahrain (BAH) and Brussels, Belgium (BRU) via Bergamo, Italy (BGY). The DHL flight was also operated by an experienced crew, who had logged almost 20,000 flight hours.

British Captain Paul Phillips was assisted by Canadian First Officer Brant Campioni, who were both DHL crew based in Manama, Bahrain. Bahrain International Airport was, and still is, DHL's main hub in the Middle East, from where the cargo airline operates to locations in the Middle East and South Asia. These include the likes of Baghdad, Cairo, Istanbul, Lahore and Sharjah, to name just a few.

The aircraft operating on this service was registered as A9C-DHL. ATDB.aero shows that it was delivered to Zambia Airways, in 1990. After various ownership changes throughout the 1990s, SNAS Aviation then transferred ownership of the aircraft to European Air Transport in 2000, which then sold it to DHL in 2002.

The crash

Peter Nielsen at ACC Zürich, the station with jurisdiction over Überlingen, was being overworked at the time as he was using two workstations due to being the only controller on duty. This was against the rules, and ultimately played a key role in the collision, as he was only alerted to the problem shortly before the crash occurred.

When he noticed a collision was imminent, at around 23:34 local time, he instructed the Tu-154 to descend to avoid hitting the 757. All being well, this would have kept the two aircraft a suitable distance apart from each other in terms of altitude, despite their paths crossing simultaneously over the south of Germany.

However, the Russian crew's traffic collision avoidance system had instructed them to climb independently of Nielsen's instruction. Concurrently, the 757's TCAS had advised the DHL crew to descend to avoid a crash. However, confusion between the two instructions meant that both aircraft descended, and they ultimately collided at an altitude of 34,980 feet, sadly killing everyone onboard.

Aftermath and investigation

An investigation was carried out by Switzerland (which had jurisdiction over the airspace), Russia (where the Bashkirian Airlines aircraft was registered) and Bahrain (where the DHL Middle East aircraft was registered). They all came to the agreement that miscommunication was a major factor that led to this crash.

However, they did disagree on where to put the blame. Bahrain thought that the private company that hired Nielsen should have been responsible, as he had been overworked. Switzerland and Russia disagreed on whether the Russian pilots were to blame, as they did not listen to Nielsen's repeated requests to climb.

The story had a final tragic twist just under two years later. In February 2004, Nielsen was murdered by the father and husband of three of the victims onboard the Tupolev, with the perpetrator spending less than four years in prison.

Sources: ATDB.aero, Aviation Safety Network