As rescue workers continued their grim harvest of the bodies and aircraft parts strewn over the idyllic countryside of southern Germany, Swiss and Russian officials began blaming each other for the mid-air collision of a Russian passenger jet and a cargo plane that left 71 people dead.
German air-accident investigators and Swiss air-traffic controllers, who were in charge of the air space over Lake Constance where the collision happened, said the two planes smashed into each other after both began steep dives in an effort to avoid just such an accident.
Anton Maag, the Swiss regional air-traffic control chief, said the pilot of the Tupolev-154 belonging to Russia's Bashkirian Airlines began its descent only after controllers repeatedly ordered it to do so.
At the same time, the pilot of the Boeing 757 cargo jet operated by DHL Worldwide Express was conducting the same manoeuvre after its collision-avoidance system advised it to take evasive action.
The result was a catastrophe minutes before midnight Monday, 11,000 metres above the lake, a favourite tourist destination.
All but 17 of the 69 people aboard the Russian jet were children and teenagers from Russia's Ural region en route from Moscow to Barcelona for a beach vacation. Also killed were the British captain of the DHL plane and his first officer, 35-year-old Brant Campioni, who grew up in Vancouver but worked out of Bahrain.
Russian officials angrily denied Swiss suggestions that the Tupolev pilot was at fault. "My version is that the air-traffic controllers are to blame," Bashkirian Airlines director-general Nikolai Odegov said at a news conference in Moscow.
"The crew fully complied with orders received from Swiss air-traffic controllers," Mr. Odegov said. Alexander Neradko, head of Russia's state civil-aviation service, blamed human error for the crash, but said the Swiss account sounded "like someone who's looking to put the blame on someone else's shoulders."
The Swiss later revised their original suggestion that their controller had given the Russian plane two minutes notice to change course after German safety investigators said the pilot was given 50 seconds warning and reacted after receiving a second advisory 25 seconds from the first.
Mr. Maag acknowledged that the Swiss controller "was cutting it close," but said his warning time was "absolutely acceptable."
A representative of the German airline pilots union disagreed. "Normally we count on five to 10 minutes for two planes heading for a planned crossing of their flight paths to be separated," Georg Fongern told German television. "Of course, we must ask why the two planes were not brought apart earlier."
Patrick Harr, another Swiss air-traffic-control official, said it was still not clear why the collision avoidance system on the Boeing 757 told the crew to dive when the Tupolev was doing the same.
"There are two mysteries," he said. "Firstly, why the Tupolev pilot didn't react straight away. And secondly, why the automatic warning system of the Boeing also gave a descent order."
German aviation officials said the handover from German to Swiss controllers went normally. Gregor Thamm of German air-traffic control said it is not unusual for two jets to be at the same altitude when they enter a common airspace, leaving it up to new controllers to order adjustments.
Swiss air-traffic control took over responsibility for the cargo plane at about 11:23 p.m. and for the Russian plane at about 11:30 p.m.
The accident occurred just after 11:35 p.m., a time when a single air-traffic controller was on duty in Zurich because a colleague was on a break, Swiss investigator Jean Overney said. The controller was being treated for shock yesterday and had not been questioned.
The two large aircraft broke into several large pieces, and their contents were scattered over fields, forests and villages surrounding Ueberlingen, a charming tourist town of 20,000 that is popular with cyclists and hikers.
"We came across five bodies just lying in the field next to each other," said Wolfgang Steiner, a gardener at a children's home about 200 metres from where the Tupolev's tail section plummeted to Earth. "One has his neck broken, one was missing a foot, but there was not blood. They were adults, but they looked so small lying in that field," he told Reuters.
Flight recorders from both planes were found yesterday.