GERMAN teams resumed the hunt yesterday for clues to the cause of a midair crash that killed a planeload of Russian children, but officials have already started trading blame. Rescuers recovered the planes’ flight data recorders and cockpit voice recorders. And a total of 37 bodies were recovered by yesterday. German crash investigators were to examine all the recorders, which could provide vital clues to the cause of one of Germany’s worst air disasters.As the international investigation got under way, Swiss air traffic control acknowledged that its collision warning system, which alerts controllers to the danger of a collision, was down for maintenance at the time of the crash. The planes had just entered into Swiss air space at the time.Swiss air traffic controllers, in charge of Lake Constance airspace, said the Tupolev reacted too slowly to their orders to drop to a lower altitude. They said the Russian pilot got Swiss orders to descend a “good minute” before the collision. German Transport Minister Kurt Bodewig said the warning was given 50 to 60 seconds before the crash. Bashkirian Airlines denied the Tupolev crew had made any mistakes. “It is the opinion of our company that the air traffic control was at fault,” said Nikolai Odegov, the airline’s director. He was in Germany as part of a Russian crash investigation team. The two planes were flying at an altitude of 35,300 feet (12,000m) above Ueberlingen at the northwest end of Lake Constance when they collided, Swiss air traffic controllers said. They said it was only on the third instruction that the Russian pilot had begun to reduce altitude to avoid collision. By the time the Tu-154 began to descend, the Boeing 757 was also diving, apparently instructed to do so by its on-board collision-avoidance system. (SD-Agencies)