ÜBERLINGEN, Germany – Swiss authorities said a collision-warning system was out of service in the Zurich tower when it took control of a Russian airliner and a cargo jet shortly before they collided at 35,000 feet, killing 71 people, mostly children headed for an end-of-school beach holiday.
As an international investigation began, Swiss air traffic control also acknowledged Wednesday that one of the two controllers on duty had broken regulations by being out of the tower for a break during the maintenance operation on the warning system — which alerts controllers to the danger of a collision.
Patrick Herr, a spokesman for Swiss air traffic control, said it was "a purely theoretical question" whether the system alone could have prevented the disaster.
"Many signs point to an exceptionally unlucky combination of circumstances," Herr said.
Maintenance on the warning system typically is done during periods of light air traffic. Monday's collision happened shortly before midnight.
Other investigators from the team dispatched to Germany by Russian President Vladimir Putin met with local investigators in the nearby town of Friedrichshafen. Salvage crews were expected to move pieces of the shattered, twisted wreckage to the Friedrichshafen airport soon so investigators can examine them.
The Russian charter jetliner and a Boeing 757 cargo plane collided late Monday over Germany, leaving a 20-mile wide debris field near Überlingen, a vacation spot set in rolling hills and forests on Lake Constance across from Switzerland. Five U.S. investigators were also expected on the scene.
Police spokesman Michael Kuhn said nine more bodies were found after the search resumed at dawn, bringing the total to 37.
Russian investigators concentrated on a large section of the Russian Tu-154 aircraft's fuselage, which lay about 500 yards from where three engines from the tail of the aircraft were embedded in a charred corner of a golden barley field.
Investigators believe as many as 20 more bodies of passengers and crew may be in the fuselage, still strapped into their seats, but have not yet been able to get inside to know for sure, Kuhn said.
The children, standout students from the city of Ufa, were on their way to a Spanish beach resort near Barcelona. A travel agent who helped organize the trip said Wednesday that 45 of the 69 people on the Russian plane were known to be children, fewer than the 52 reported earlier by officials.
Sergei Kolesnikov, general director of the Kreks travel agency in Ufa, said it was discovered that seven other people also boarded the flight after buying last-minute tickets through a Moscow travel agency. Their ages were unclear.
A team of 30 counselors was working with rescue workers who started asking for help Wednesday to cope with the gruesome business of recovering body parts from the crash.
"While we are working we put all our efforts into what we are doing, and it is only when we are resting that the thoughts come and then we have the shock situations," said Henning Noeh, head of the Lake Constance region fire department.
Swiss officials were already facing criticism for not giving the Russian pilot enough time to lower the Tupolev 154 he was flying for Bashkirian Airlines out of the way of the Boeing 757 cargo jet.
The Swiss officials insist the 50-second warning should have been sufficient, but a German pilot representative said pilots usually count on five to 10 minutes warning.
"Of course we must ask why the two planes were not brought apart earlier. That would have been the usual thing to do," pilots' union spokesman Georg Fongern said.
Initially, Swiss air traffic control said it gave the Russian plane about two minutes' warning and that the pilot responded after a third request. But the Swiss revised their account after German officials began describing the tighter time scenario.
The Russian pilot heeded the command to descend after a second warning. But the cargo jet was equipped with a radar collision avoidance system that told its pilots to descend as well.
The result was a fiery collision at 36,000 feet over Lake Constance, shared by Germany, Switzerland and Austria, and flaming chunks of wreckage raining down on farms and forests.
No one on the ground was hurt, but large pieces of the planes landed perilously close to homes, and many people saw and heard the explosion in the night sky.
Investigators from Germany's aviation authority were to begin analyzing information Wednesday from the planes' flight data recorders and cockpit voice recorders. Officials were also working to fly in relatives of the 45 children who died in the crash to the site.
Two pilots died aboard the cargo plane operated by DHL International delivery service, flying from Bahrain to Brussels with a stop in Bergamo, Italy. Their bodies were among those recovered in the first day of searching.
In Washington, White House press secretary Ari Fleischer said President Bush sent condolences "on behalf of the United States to all the families of the victims of this tragic air accident and also to the people of Russia for their loss on this sad day."
The Russian airline has defended its pilots as fluent in English with thousands of flying hours and experience on overseas missions, and pointed the finger at the controllers.