Today marks the 22nd anniversary of the mid-air collision of a chartered BAL Bashkirian Airlines Tupolev Tu-154M (RA-85816) and a DHL Boeing 757-23APF (A9C-DHL) over Überlingen, Germany, on Lake Constance near the Swiss border. The BAL aircraft was operating charter flight 2937 from Moscow (Domodedovo) to Barcelona with 60 passengers and a crew of nine. The DHL aircrat was operating scheduled cargo flight 611 with a crew of two; the flight originated in Bahrain with a stop at Bergamo before continuing to Brussels. All 71 souls aboard the two aircraft were killed.

At the time of the collision, both flights were under the control of Skygyude, the Swiss air traffic control (ATC) agency. The collision occurred at a late hour (23:35:32 CEST) and thus had a single controller (Peter Nielsen) handling two workstations covering the airspace. 50 seconds before the collision, he realized that both aircraft were on intersecting courses aand both at FL 360, and instructed the Bashkirian flight to descend 1,000 feet to FL 350. Shortly thereafter, the traffic collision avoidance systems (TCAS) aboard the two aircraft issued resolution advisories (RA) instructing the Bashkirian flight to climb and the DHL flight to descend. Had the Bashkirian pilots obeyed the TCAS instructions rather than the controller's, the accident would not have occurred.

On 24 February 2004, Vitaly Kaloyev, a Russian architect whose wife and two young children had been passengers aboard the Bashkirian flight, tracked down Peter Nielsen at his home in Kloten, near Zürich, and stabbed him to death in front of his wife and three children.

The Bundesstelle für Flugunfalluntersuchung (the German Federal Bureau of Aircraft Accidents Investigation) identified the following immediate causes:

• The imminent separation infringement was not noticed by ATC in time. The instruction for the TU154M to descend was given at a time when the prescribed separation to the B757-200 could not be ensured anymore.
• The TU154M crew followed the ATC instruction to descend and continued to do so even after TCAS advised them to climb. This manoeuvre was performed contrary to the generated TCAS RA.

In addition, they identified the following systemic causes:

• The integration of ACAS/TCAS II into the system aviation was insufficient and did not correspond in all points with the system philosophy. The regulations concerning ACAS/TCAS published by ICAO and as a result the regulations of national aviation authorities, operational and procedural instructions of the TCAS manufacturer and the operators were not standardised, incomplete and partially contradictory.
• Management and quality assurance of the air navigation service company did not ensure that during the night all open workstations were continuously staffed by controllers.
• Management and quality assurance of the air navigation service company tolerated for years that during times of low traffic flow at night only one controller worked and the other one retired to rest.

Bahrain, Russia, and Switzerland added deviating statements which were included as Appendix 10 of the final report.

Today's Featured Map approximates the two flights, with the western portion of Bashkirian 2937 in dark blue and the path of DHL 611 in red. The paths are documented in the German accident report but some of the waypoints and navaids along the path of the Russian flight have changed significantly since the accident occurred or are ambiguous, hence the map may not be entirely faithful to the flight plans.

References and additional information:

• Bundesstelle für Flugunfalluntersuchung (German Federal Bureau of Aircraft Accidents Investigation)
  • Investigation Report: near Ueberlingen/Lake of Constance/Germany (May 2024)
  • Investigation Report, Appendix 1+3
  • Investigation Report, Appendix 2-10
• Tupolev TU154M and Boeing 757-200 / Überlingen, Germany / July 1, 2002 – Federal Aviation Administration (FAA)
• Accident Tupolev Tu-154M RA-85816, Monday 1 July 2002 – Aviation Safety Network
• 2002 Überlingen mid-air collision – Wikipedia
• Skyguide
• DHL Aviation
• Planespotters.net
  • RA-85816 Bashkir Airlines Tupolev Tu-154M
  • A9C-DHL SNAS Aviation Boeing 757-23APF