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-   -   Multiple Tailstrike A320 BH Air - Italian Authority Investigation (https://www.pprune.org/accidents-close-calls/603309-multiple-tailstrike-a320-bh-air-italian-authority-investigation.html)

AN2Driver 19th Dec 2017 09:45

Multiple Tailstrike A320 BH Air - Italian Authority Investigation
 
Tail-struck A320's crew originally chose to continue flight


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: FlightGlobal - http://www.flightglobal.com/news/art...ntinue-444260/)

FlightDetent 19th Dec 2017 21:06

Abnormal Attiude Law, is that what it says? Impressive.

F-16GUY 20th Dec 2017 12:24

Why did they not abort at 30 KTS when things started to go wrong?

Anybody knows where I can find the report?

Willie Nelson 21st Dec 2017 23:13

BH AIR A320 at Verona on 1st 2009.
 
Thanks to the team at Avherald, I'm reposting this from their site. This final report has just now been released almost 8 years after the event.

The bold script is mine not Avherlds.

By Simon Hradecky, created Dec 19th 2017 17:46Z,last updated Dec 19th 2017 17:51Z

Italy's ANSV released their final report in Italian concluding the probable cause of the accident was:

The cause of the accident was a human factor. In particular the occurrence was triggered by an aircraft loading other than approved by the load and trim sheet with respect to the positions of the passengers on board, which resulted in the center of gravity being aft of the limit certified for the takeoff mass of 56 tons.

The ANSV analysed that the occurrence can be characterized as a premature rotation during start of the takeoff run when the power levers were moved into the FLX/MCT detent. The investigation was able to ascertain that the mass and balance was outside the permitted envelope, the center of gravity was aft of the limit certified for the takeoff mass of 56 tons. This condition was caused by passengers in different locations than the load and trim sheet approved by the captain required, in addition the neutral trim setting in occordance with the approved load and trim sheet was thus not congruent with the actual position of the center of gravity. Therefore an uncontrolled rotation occurred in the initial phase of the takeoff run triggered by the pitch moment produced by the accelerating engines.

The ANSV analysed that there had been no time pressure, the aircraft arrived in Verona on schedule and without any anomaly. The aircraft departed the gate 15 minutes ahead of schedule reducing the planned transit time from 45 to 30 minutes. The ANSV wrote: "it should be stressed that the early departure showed the will of the flight crew to speed up transit and this precisely is the reason why the load and trim sheet was the last to arrive on board when the aircraft was already ready for departure." Based on the testimony by the ramp agent, who reported to have warned the flight crew, it is such conceivable that the warning by the ramp agent to re-balance the passengers was not understood or not considered. The testimony by the cabin manager stands in contrast to the ramp agent stating that the ramp agent had not provided any warning to move the passengers. The apparent communication problem might be the result of people of various nationalities communicating in English in an already excited state to depart.

The ANSV further analysed that the first officer, apparently pilot flying, did not push the stick half way forward to counter any pitch moment induced by the engine acceleration as standard operation recommends. However, the outcome of pushing the stick half way forward can not be predicted given that the aircraft was operated outside its CG limits. Following the unexpected pitch up by the aircraft at around 50 knots both pilots (dual input) pushed their side sticks fully forward which stabilized the pitch angle at 11 degrees, however, without returning the nose wheels onto the runway surface, the thrust levers were briefly moved back, the engines began to respond and spool down, then the thrust levers were pushed into the TOGA detent. The first officer returned his stick to the neutral position, the captain have a nose up input, which increased the pitch angle to 12.7 degrees causing the tail to contact the runway surface.

The ANSV analysed that obviously the captain intended to reject takeoff when the aircraft began to rotate unexpectedly at 50 knots, both pilots pushed the sticks forward, the thrust levers were moved aft, but then the captain decided otherwise and continued takeoff moving the thrust levers into the TOGA detent. The captain obviously realized following the decision to reject takeoff, that the thrust reduction would result in a rapid de-rotation resulting in a violent impact of the nose gear on the runway.

The decision to continue the flight to Rome was influenced by factors other than flight safety. The crew must have realized that a tail strike had occurred, the FCOM requires an immediate return to the point of departure. Considering the type of charter operation in the absence of any stand by aircraft at an airport without assistance by maintenance leads to the hypothesis that the crew, although aware of the tail strike, had underestimated the technical consequences trying to reach the final destination in order to avoid delay or cancellation of the flight and postponed the assessment of the damage to Rome. The subsequent cabin pressurization warning prevented the flight to Rome and prompted the crew to return to Verona. The lack of CVR recording available for the takeoff phase prevented to determine the decision making and thus verification or falsification of that hypothesis though.

The ANSV had earlier reported the CVR was successfully downloaded and contained 30 minutes of recording, however, only the last phases including landing of the accident flight, but not the takeoff phase, which had been overwritten already.

Tracks on the runway (Photo: ANSV):
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Map (Graphics: ANSV):
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By Simon Hradecky, created May 5th 2011 13:53Z,last updated May 5th 2011 13:55Z

The Italian ANSV reported in their preliminary report, that the flight had originated in Hurghada (Egypt) and was destined for Rome Fiuminichino via an intermediate stop in Verona.

At the time of departure from Hurghada the aircraft carried 77 passengers destined for Verona and 87 passengers for Rome. The passengers to Verona were mainly seated in the forward and central cabin, the passengers to Rome mainly in the central to aft cabin. The luggage for Verona had been stowed in the forward cargo compartment and the luggage for Rome in the aft cargo compartment.

After arrival in Verona the passengers for Verona disembarked and their luggage was unloaded, the passengers to Rome kept their seats and their luggage was not re-distributed.

A load and trim sheet was produced at Verona that showed the remaining passengers to Rome in different seat allocation than on the leg Hurghada-Verona. This was not detected by the crew nor did the crew consider to re-distribute the passengers.

The crew decided that no re-fuelling was necessary.

During the takeoff, as soon as the power levers were advanced for FLEX takeoff, the aircraft started an uncommanded early rotation causing a tail strike, the takeoff however was continued with the flight controls degradated to alternate and direct law. The aircraft became airborne at 113 KIAS, a stall warning activated immediately after takeoff and lasted for 5 seconds. The crew continued the departure and the climb until a master caution indicating a cabin pressurization fault activated, then the crew decided to return to Verona.

Inspections revealed substantial structural damage to the lower part of the tail fuselage compromising the pressurized compartment.

The preliminary investigation noted following findings:

- all baggage and cargo were located in the after (nr. 3) cargo compartment in accordance with the Load and Trim sheet;

- the 87 passengers with final destination Rome Fiumicino were seated as per their initial seat assignment given at Hurgada and not in accordance with the Load and Trim sheet prepared in Verona;

- the Load and Trim sheet approved by the captain, was prepared by Verona handling agent in order to respect the new mass and balance configuration requiring the remaining passengers seating to be considerably different from their seat assignment in the incoming flight

- the captain did not consider or did not notice that, based on the Load and Trim sheet, the remaining passengers should have been distributed in order to equally balance their seating on board in the three cabin areas; this resulted in having the passengers seated so as to occupy all the after cabin seats with only few passengers seated in the central and forward cabin

- the center of gravity position calculated considering the effective distribution of passengers and cargo on board, was outside the after operational envelope limit for takeoff.

Two safety recommendations were issued as result of the investigation so far.

Damage to the tail section (Photo: ANSV):
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By Simon Hradecky, created Sep 1st 2009 22:09Z,last updated Sep 2nd 2009 09:55Z

A BH Balkan Holidays Air Airbus A320-200 on behalf of Air Vallee, registration LZ-BHC performing flight DO-5379 from Verona to Rome Fiumicino (Italy), struck its tail onto the runway in Verona while becoming airborne. The crew decided to return to Verona.

The Italian National Agency for Aviation Safety (ANSV) launched an investigation stating, that the damage to the airplane prompted the agency to rate the occurrence an accident. According to ANSV the airplane was doing Verona-Rome-Hurghada.

According to the airport of Rome Fiumicino the airplane was due to arrive from Hurghada via an intermediate stop in Verona.

Sources at Verona Airport said, that the luggage of those passengers getting off at the stopover in Verona (arriving from Hurghada) had all been stored in the forward luggage hold, while luggage of passengers carrying on to Rome was in the rear luggage hold. The forward hold was therefore emptied during the stopover.

JammedStab 22nd Dec 2017 00:09

Thanks,

Continuing a takeoff when the aircraft starts rotating by itself at a very low airspeed is not a good idea.


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