Colombian investigators have determined that the crew of a Boeing 727-200 freighter departed in a tailwind before the aircraft overran and struck a perimeter fence, briefly becoming airborne before crashing in a field.
The inquiry into the 20 December accident at Puerto Carreno states that the crew was apparently “unaware” of information regarding the direction and strength of the wind.
Colombian accident investigation authority GRIAA says preliminary information shows two aircraft – an Embraer 170 and a Cessna 208 – took off from runway 07 shortly before the 727 was due to depart.
These two aircraft had taken into account the prevailing wind at the airport, it says. Meteorological data showed the wind from 10° at 8kt, which would have favoured a take-off from 07.
But GRIAA says cockpit-voice recorder information shows the 727 headed instead to the threshold of the opposite-direction runway 25. It points out that Puerto Carreno was operating as an uncontrolled airport from 15:00, and the 727 departed at around 17:20.
Flight-data recorder information indicates that the trijet was configured with 30° take-off flaps. The inquiry associates this setting with a modification known as the ‘Quiet Wing’ which was developed for the 727 in order to reduce noise.
The ‘Quiet Wing’ system is designed to increase take-off performance through modifications including a flap and aileron droop, to increase lift and thereby cut perceived noise on the ground.
GRIAA adds that the 727’s configuration also included 6.5 units of elevator trim.
The inquiry says the evidence suggests the crew was not aware of the wind situation. Departing from runway 25 under the recorded wind conditions would have resulted in a 4kt tailwind component rather than a 4kt headwind.
GRIAA says the air temperature was 31C. The airport has an elevation of 54m and a runway length of 1,800m.
All three engines were functioning during the take-off roll. The investigators state that the aircraft’s V1 and rotation speeds were 127kt.
Evidence from video images of the ill-fated departure show the aircraft overran and hit a perimeter fence – tearing out a 13m-wide section – before striking a small military structure and a tree, which sheared off the right main landing-gear and the starboard inboard flap.
Cockpit-voice recorder information shows the crew determined that the starboard engine had lost thrust and there was a loss hydraulic fluid following the impact.
The 727 managed to climb to 790ft but entered a slow turn to the right, with its bank angle gradually increasing to 60°. It remained airborne for around 2min but its airspeed bled away, the resulting loss of lift caused the aircraft to lose height, and it struck the ground about 4nm from the threshold of runway 07.
GRIAA says ground-proximity alerts and stall warnings had been sounding in the cockpit, and the crew was carrying out a fuel-jettison procedure.
The jet struck the ground at a large angle of bank, it states, with high horizontal speed but relatively shallow pitch.
One of the six occupants of the freighter survived the crash. The cockpit and empennage were among the main components to emerge from the debris field.