High Quality Content by WIKIPEDIA articles! Bashkirian Airlines Flight 2937, registration RA-85816, was a Tupolev Tu-154M passenger jet en route from Moscow to Barcelona. DHL Flight 611, registration A9C-DHL, was a Boeing 757-23APF cargo jet flying from Bergamo, Italy, to Brussels, Belgium. The two aircraft collided in mid-air on 1 July 2002, at 21:35 over the towns of Owingen and Überlingen in Germany, killing all 71 aboard both aircraft. The German Federal Bureau of Aircraft Accidents Investigation determined on 19 May 2004, that the accident had been caused by problems within the air traffic control system and problems with the use of the collision warning system. On 24 February 2004, Peter Nielsen, the controller who was on duty at the time of the accident, was stabbed to death by Vitaly Kaloyev who had lost his wife and two children in the accident. Flight 2937 was a chartered flight carrying 60 passengers and 9 crew. 45 of the passengers were Bashkortostan schoolchildren on a school trip to the Costa Daurada area of Spain, which was organized by the local UNESCO committee. Most of the parents of the children were high-ranking officials in Bashkortostan.