By David Learmount in London

A Bombardier Learjet 35A air ambulance took off at night under visual flight rules (VFR) and crashed into a mountain after an air traffic controller gave the crew a heading towards high terrain, according to a US National Transportation Safety Board (NTSB) preliminary report on the 2004 accident. All five people on board were killed.

The positioning flight, carrying two pilots and three medical staff, triggered the air traffic controller’s minimum safe altitude warning system (MSAW), but the controller did not advise the pilots, says the NTSB, adding that fatigue may have contributed to the pilots’ “degraded decision-making”.

On 24 October 2004 the Med Flight Air Ambulance Learjet took off from Brown Field airport in San Diego, California cleared under VFR to climb to 5,000ft (1,525m) while awaiting its instrument flight rules (IFR) clearance, but the crew elected to level off at 2,300ft “presumably to maintain VFR below the cloud”, says the NTSB report. It notes that the recommended procedure at night in mountainous areas, even under a VFR departure, is to follow the standard IFR departure pattern, but the crew did not do this.

“The air traffic controller who handled the aircraft provided the flight crew with a heading that allowed [it] to continue toward a mountain. The controller also failed to alert the flight crew of the aircraft’s proximity to terrain and of the MSAW alerts that were generated by his [the controller’s] computer system,” says the NTSB. At the time of the accident the captain had been awake 17 hours, the co-pilot 16 hours, and both pilots had accumulated 11 hours duty time.

Source: Flight International