Carrying three soldiers and two pallets of mortar shells through the Hindu Kush mountains of Afghanistan, the twin-engine turboprop was on a military mission.
But Flight BW61 from Bagram air base was technically an air taxi, according to civilian safety officials. That distinction may have contributed to a Nov. 27, 2004, crash that killed everyone on board -- and may put at risk thousands of military passengers and thousands of tons of cargo carried every year by contractors in war zones.
Neither military nor Federal Aviation Administration safety rules were enforced on the flight, which was operated by a subsidiary of Blackwater USA, which is based in Moyock, N.C.
Standard safeguards -- high-altitude oxygen masks and at least one pilot experienced with the terrain -- were not observed. There was no dispatcher to send an alert that the plane was missing, which delayed rescuers' arrival and may have compounded the tragedy.
The three-man crew and two of the passengers died on impact, a military investigation found.
But a third passenger apparently lived for at least eight hours, long enough to climb out of the plane, smoke a cigarette and unroll two sleeping bags before dying of internal injuries.
The safety lapses emerged in investigations by the military and the National Transportation Safety Board and in a lawsuit that families of the crash victims filed against Blackwater, which is seeking to have the suit thrown out in federal court.
With two American-flag carriers and three foreign companies performing contract work for the military in Afghanistan and Iraq, other flights could also be in peril because of gaps in regulation.
Though the NTSB recommended in December that the military and the FAA coordinate on oversight of flights operated by military contractors, the FAA responded this year that it would not give a progress report for six months.
The Pentagon, though, said Blackwater would begin auditing its own flights in Afghanistan and reporting the results to the government. While the FAA does not fly on the planes in Afghanistan, the Defense Department said that government quality assurance personnel "randomly fly" on them.
Even though Flight BW61 was operating in Afghanistan, the FAA had jurisdiction over it because the agency considered it an American air taxi. The plane, a Spanish-made CASA 212, was operated by Presidential Airways, the Blackwater unit that won a $35 million contract in September 2004 from the Pentagon's Air Mobility Command. The Pentagon needed small planes to carry cargo and passengers at high altitudes to rough landing strips.
The crew's unfamiliarity with the route is clear from the cockpit voice recorder transcript.
"I hope I'm goin' up the right valley," said the captain, Noel B. English, according to the transcript. "We'll see where this leads."
Robert F. Spohrer, a lawyer for the families of the dead passengers, argued that if the flight had been operated by the military, better safeguards would have been imposed.
"This was infinitely worse than any armed forces flight would have been," he said. "It would have had triple redundancy, with checklists. In the military, you plan your flight and fly your plan. These guys did neither."
The flight did not follow some civilian rules, either. The NTSB, for example, concluded that the pilots were not wearing oxygen masks, as air taxi operators are required to do in unpressurized cabins at that altitude.
And no one on the ground tracked the plane from takeoff to landing, as federal civilian safety rules require.
The Defense Department has a system for tracking its own planes, and even in areas with poor radio communication, the military takes notice immediately if a flight is overdue.
But no search was launched for Flight BW61 until the plane was overdue for its return to Bagram, which was about seven hours after the crash; rescue forces spent the first five hours looking in the wrong place.