The pilots' failure to follow established procedures was the probable cause of the fatal crash of a British Aerospace "Jetstream" BAE-J3201 twin turboprop in October 2004, the NTSB said on Tuesday. Fatigue was likely a contributing factor. The Jetstream, on a scheduled flight from St. Louis, crashed short of the runway at Kirksville (Missouri) Regional Airport during a night non-precision instrument approach in instrument meteorological conditions. The two pilots and 11 passengers died, and two passengers were seriously hurt. The NTSB said the pilots descended below the minimum descent altitude before required visual cues were available and failed to follow the established division of duties between the flying and non-flying pilot. The pilots had been on duty since 5:30 a.m. at the time of the crash, over 14 hours later, and were making their sixth landing of the day. "It is imperative that pilots understand and follow proper procedures when flying in demanding conditions," said NTSB Acting Chairman Mark Rosenker. "Pilots are also expected to perform in a professional manner at all times when operating an aircraft ... The discipline in that cockpit didn't seem to exist, which really created an environment for mistakes to be made." Both pilots were looking for the approach lights and failed to monitor the airplane's descent rate and altitude, the NTSB said. The pilots failed to maintain professional demeanor and indulged in nonessential conversation while below 10,000 feet, contrary to established sterile cockpit regulations. At our deadline, the final report had not yet been posted, but a synopsis from Tuesday's meeting was online.