Air Greenland has revised its centre-of-gravity considerations after a serious incident in which a Bombardier de Havilland Dash 8-200 failed to rotate on departure owing to higher-than-assumed passenger and baggage weights.
The turboprop had been conducting its take-off roll from Nuuk’s runway 05 and had reached its rotation speed of 88kt, but when the first officer pulled back on the control column there was no response from the aircraft.
This prompted the first officer to abort the take-off by reducing throttle and applying maximum anti-skid braking, and the aircraft stopped about 50m from the end of the 950m runway. The surface was dry at the time.
Twenty-nine passengers and three crew members had been on board the 30 May service to Kangerlussuaq, which meant the aircraft was fully laden.
Pre-flight calculations – using standard weight figures for the occupants – had assumed a cabin weight of 2,445kg, evenly distributed, and this resulted in a centre-of-gravity within the aircraft’s limits.
But the actual weight was closer to 2,740kg with the first three rows of seats particularly heavy, at over 160kg more than the assumed figure. The pilots’ weight was also heavier, and the overall discrepancy across the crew, passengers, baggage and wardrobe amounted to a 13% increase.
Danish investigation authority HCL says the crew had been “aware” of a forward centre-of-gravity issue before departure, and an off-duty crew member had repositioned from the cockpit jump-seat to the cabin.
But the inquiry found that the centre-of-gravity – when calculated using actual, rather than assumed, weights – was still 2.4in (6.1cm) forward of the aircraft’s operational limitation.
Even though the aircraft had reached rotation speed during the take-off run, the crew chose to abort after believing the lack of response signified a flight-control failure.
“The rationale behind the decision on aborting the take-off roll complied with the operating procedures and potentially prevented a more severe outcome,” says the inquiry.
Air Greenland has since revised its centre-of-gravity envelope to account for increased passenger weights, and amended its method of passenger distribution during seating to achieve greater control of extreme forward or aft positioning.
Although operating procedures require ground personnel or cabin crew to advise the captain if significant numbers of larger-than-average passengers are on board, the inquiry questions the effectiveness of this method of risk control.
“Such observations…are affected by, for instance, culture, subjective perception, working experience, and individual training,” it states.
Given the severity of the Air Greenland incident, the inquiry has urged the European Union Aviation Safety Agency to revisit its plans to update standard passenger data, a task which the investigators claim has been deprioritised by EASA.
Source: FlightGlobal.com
