FRANKFURT, Germany, July 1 (UPI) -- Pilot error is being blamed Tuesday for a mid-air collision between a DHL freight plane and a Russian passenger airliner over southern Germany that killed more than 70 people, including students on a school trip to Spain.
"Ground control demanded that the Tupolev lower its altitude. Despite several calls, it did not react," Ulrich Mueller, the transport minister for the Baden-Wuerttemberg region, said.
He said he had been give his information by Swiss air traffic controllers.
"We have to assume right now that this was a misunderstanding," he said.
Monday night's mid-air collision occurred at an altitude of 36,000 feet. Due to the height, the debris was spread over a 20-mile radius.
Bashkirian Airlines, to whom the Tupolev 154 belonged, said the flight had 57 passengers and 12 crew. The students were on their way to Spain for a trip. The plane was flying from Ufa, the capital of Russia's republic of Bashkortostan, to Barcelona, Spain, and had made a stopover in Moscow.
The DHL plane was flying from Bahrain to Brussels, and had made a stopover in Bergamo, Italy.
DHL spokesman Axel Geitz said the company offered its "condolences" to the families of the dead.
Russia's ITAR-TASS news agency identified the Tuplev's pilot as Alexander Gross. The British Broadcasting Corp. identified the Boeing's pilots as Paul Philips. His co-pilot was reportedly Canadian.
Both pilots aboard the DHL 757 were killed in the crash near Lake Constance on the Swiss-German border. Debris fell near the town of Uberlingen and set several buildings on fire. No local casualties were reported.
Local media reported recovery workers found the flight data recorder of one of the planes near the town of Gerdwangen-Eringen, on the shore of Lake Constance. Hundreds of policemen and rescuers are taking part in the effort.
The single-aisled Boeing 757 can carry more than 200 passengers, according to the company's Web site. The Tupolev can carry 180 passengers.