Investigators have disclosed that the crew of an unbalanced Airbus A320 which sustained several violent tail-strikes during take-off from Verona initially chose to continue the flight in breach of operating regulations.
Italian investigation authority ANSV had previously determined that 77 passengers had disembarked at Verona, after the BH Air jet arrived from Hurghada, but that the remaining 87 passengers flying onwards to Rome were not redistributed. Fifty-eight of these passengers had been in the aft cabin and another 25 in the centre cabin, with just four up front.
The passengers were supposed to be redistributed with 29 seated in each cabin. This would have fixed the centre of gravity at 29.1% of mean aerodynamic chord, within the appropriate limits for a 56t take-off weight.
But although the ramp agent told ANSV that he had submitted a load and trim sheet to the captain, and had told the cabin manager that passengers need to be reseated, this redistribution was not carried out – possibly owing to a language misunderstanding. The captain nevertheless approved and signed the load sheet.
ANSV's full inquiry into the event states that the pilots used the 'flex' thrust setting for departure on runway 04 but, against normal procedures, did not apply forward side-stick pressure as the aircraft began to roll.
The aircraft, with flaps at 10° and slats at 18°, began to lift its nose at just 30kt and both pilots pushed their side-sticks fully forward as the pitch reached 11°.
Seven seconds into the take-off roll the captain momentarily reduced thrust before instantly increasing it to maximum. As the aircraft reached 60kt it struck its tail on the runway, and further fluctuations, with lower intensity, showed the jet suffered "repeated" strikes, says the inquiry.
With its high nose-up attitude of 15° the aircraft, having gained sufficient lift, became airborne at an airspeed of around 110kt. The pitch increased to 23° and, at 125kt, a stall warning sounded for 5s. The jet switched from direct to alternate flight-control law and a cabin altitude warning, indicating pressurisation problems from the damaged fuselage, sounded as it climbed through 9,750ft.
ANSV says that the crew had decided to continue the flight, "contrary" to operating procedures which required an immediate return to the airport in case of tail-strike, and had requested to maintain 10,000ft and proceed to Rome.
The crew opted to return to Verona "only after the activation of [the pressurisation warning]", the inquiry adds, and did not specify the reason to air traffic control.
Airbus analysed the aircraft's load distribution and calculated that its centre of gravity would have been 43.75% of mean aerodynamic chord, outside the operating limit.
The inquiry says the crew's choosing initially to continue the flight suggests the decision-making process was influenced by "factors unrelated to the simple objective of flight safety".
While assessing the extent of tail-strike damage in flight is "not easy", it states, the pilots must have realised that the impact occurred during take-off. The precise decision-making situation could not be clarified because the cockpit-voice recorder data for the initial part of the flight was unavailable.
None of the occupants was seriously injured in the event, on 1 September 2009, although four of those in the rearmost row were treated for whiplash.
Source: Cirium Dashboard