The search for clues as to what caused yesterday’s fatal plane crash at Amsterdam’s Schiphol Airport has been continuing throughout the night. Authorities say nine people, including the pilot and co-pilot, were killed and 84 were injured when a Turkish Airlines Boeing 737 plunged some 600 metres into a field close to the runway.Relatives of the 134 passengers and crew – for the most part Turkish – have been arriving at hospitals where the injured are being treated. Doctors say six are in a critical condition. Dutch Prime Minister, Jan Peter Balkenende, has visited the site and spoken to emergency services personnel. It is the worst crash at the Netherlands’ main airport since 1992, when 43 people were killed after a cargo plane hit a building on take-off.