Colombian investigators are recommending prohibition of an improved take-off climb procedure if tailwind conditions are likely, following the accident involving a departing Aerosucre Boeing 727-200 freighter at Bogota.
The aircraft’s prolonged take-off run from runway 14L resulted in its striking the ILS localiser antenna, some 300m beyond the runway end, as well as a 6.4m pole located in a parking lot another 173m further on.
It managed to climb away, despite sustaining wing and undercarriage damage, and subsequently returned to land on runway 14R.
While the Colombian accident investigation authority DIACC has yet to reach conclusions on the 10 November occurrence, it has pointed out that the 727 can conduct an improved procedure to enhance take-off and climb performance at high-altitude airports.
This involves setting maximum thrust and using higher speeds for rotation and initial climb, ensuring a wider safety margin, better stability and optimum lift-to-drag ratio.
But the speed increase means the procedure also demands more runway length, especially if aircraft are operating at high weights, conducting a rolling take-off, or departing in hot-and-high conditions.
If a tailwind is present, says DIACC, this can “further complicate” the situation because it extends the take-off roll and reduces the aircraft’s climb capability.
Preliminary findings from the inquiry state that, during taxiing, wind conditions were “not favourable” for take-off because they carried a 12kt tailwind component.
An aircraft ahead of the 727 was holding on 14L because of the wind. After 15min, the wind began to weaken, and this preceding aircraft departed.
The 727 crew was cleared for take-off after being advised that the wind was 9kt from 280° – which suggests a tailwind component of 7kt.
DIACC says the captain, who was flying, carried out a rolling take-off from 14L which took up the “entire length” of the runway.
As the aircraft rotated, the crew felt a “strong jolt” which they thought related to the landing-gear, says the inquiry.
The 727, which had been bound for Valencia in Venezuela, initially followed the ZIP5H departure pattern but the crew, having considered the situation, opted to return to Bogota.
After holding at 15,000ft in the vicinity of the VULAM waypoint, north of the airport, in order to burn fuel, the aircraft conducted an approach to 14R and landed about 1h after taking off.
Inspection of the jet determined that it had sustained damaged to its left wing, including the outer leading-edge slat, the aileron and inboard flap. Its tail-skid was damaged, and one of its left-hand main landing-gear tyres had burst.
None of the five occupants – two pilots, a flight engineer, technician and dispatcher – was injured.
DIACC says the aircraft’s weight-and-balance documents indicated a cargo of 12 pallets weighing 42,600lb (19,300kg) and a total fuel load of 33,500lb. The cargo was removed for weight verification as part of the investigation.
According to the inquiry the carrier, almost exactly two years earlier, had informed Boeing 727 and 737 crew members – including those involved in the accident – of operational limitations for take-off in tailwinds.
Measures implemented included a recommendation that take-off be suspended if the tailwind exceeded 5kt on the active runway. A joint assessment with tower controllers regarding wind conditions would also be carried out, with consideration given to delaying departure or changing the take-off runway.
As it continues to investigate the Bogota accident, DIACC has recommended prohibiting the improved take-off climb procedure in tailwind conditions – or if variable winds present the possibility – because such a scenario “significantly increases operational risks”.
