Employees of Swiss air traffic controllers "Skyguide" go on trial in a Zurich court to decide whether they are responsible for the July 2, 2002 plane crash above Lake Constance when a Bashkirian Airlines plane crashed with a DHL cargo plane, killing 71 people, most of them youths. Swiss prosecutors opened criminal proceedings against eight employees of air traffic control firm Skyguide on Tuesday (May 15) over a 2002 mid-air collision that killed 71 passengers, most of them children. The crash involving a Russian holiday charter and a freight plane occurred in Swiss-controlled airspace over southern Germany after a lone air traffic controller missed a warning on his radar screen -- one in a chain of errors that led Skyguide to admit serious flaws. It also triggered a round of soul-searching in wealthy Switzerland, a country as well-known for public order and the quality of its services as for the beauty of its landscape. Five years after the disaster, one of Europe's worst-ever peacetime air accidents, the Swiss are still trying to answer the question of who exactly was to blame. "I hope that we will have a fair trial and I hope that we will get some convictions for the accused," State Prosecutor Bernhard Hecht told reporters as he arrived at the court. The controller on duty that evening, Peter Nielsen, was later stabbed to death by a bereaved Russian man who lost his wife, son and daughter on the flight. On trial are eight Skyguide employees charged with manslaughter for contributing to unusual circumstances that caused the mishap. The public prosecutor has requested sentences ranging from 6 to 15 months. Both the main telephone and the backup telephone were out of order, the radar software that displays flight coordinates was in a restricted mode and Nielsen's only backup was on a coffee break when the two planes collided. The Russian Tupolev holiday charter flight had 57 passengers, mostly children, and 12 adult personnel on board. The Boeing 757 flight from logistics firm DHL had 2 pilots aboard. The Russian plane obeyed Nielsen's order to dive at the same time the DHL freight flight obeyed its on-board anti-collision system, which told it to dive as well, leading the two craft to collide at an altitude of 11,000 meters (35,000 feet). The head of Skyguide later asked for forgiveness and the Swiss president offered an official state apology to Russia. The government-owned company Skyguide continues to suffer, five years on, from an acute shortage of personnel and a budget shortfall.