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A321, Manchester UK, 2011 (2)
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|On 23 December 2011, an Austrian Airlines Airbus A321 sustained a tail strike at Manchester as the main landing gear contacted the runway during a night go around initiated at a very low height after handling difficulties in the prevailing wind shear. The remainder of the go around and subsequent approach in similar conditions was uneventful and the earlier tail strike was considered to have been the inevitable consequence of initiating a go around so close to the ground after first reducing thrust to idle. Damage to the aircraft rendered it unfit for further flight until repaired but was relatively minor.|
| Actual or Potential
|HF, LOC, WX|
|Type of Flight||Public Transport (Passenger)|
|Intended Destination||Manchester International Airport|
|Actual Destination||Manchester International Airport|
|Location - Airport|
|Airport||Manchester International Airport|
|Tag(s)||Inappropriate crew response - skills deficiency|
|Tag(s)|| Flight Control Error|
Unintended transitory terrain contact
|Tag(s)||Low Level Windshear|
|Damage or injury||Yes|
|Causal Factor Group(s)|
On 23 December 2011, an Airbus A321-200 being operated by Austrian Airlines on a passenger flight from Innsbruck to Manchester sustained a tail strike as the main landing gear made contact with runway 23R soon after the initiation of a go around from a very low height in night VMC following handling difficulties due to the prevailing wind shear. Damage to the aircraft rendered it unfit for further flight until repaired but was relatively minor.
An Investigation was carried out by the UK AAIB. FDR data was recovered and successfully replayed. The sequence of events was reconstructed to examine the effect of the difficult conditions on aircraft handling during the final stages of the approach and the commencement of the go around. It was noted that the First Officer was PF and that neither of the crew had previously operated to Manchester. When checking their pre flight briefing material on the destination, the only significant point noted was in respect of the runway 23R longitudinal profile.
It was noted that the significant north westerly crosswind which prevailed (mean direction from 320º) was routinely associated with difficult wind shear on the final approach used because of the extent to which the upwind terminal buildings complex created mechanical turbulence. It was noted that as a result of these known effects of the prevailing crosswind, the airport authority had declared a ‘weather standby’ some three hours earlier. This action was taken in recognition of the deterioration of weather conditions to “such an extent as to render the landing of aircraft more difficult” and required the precautionary deployment of RFFS vehicles to a series of designated ‘forward positions’ near the runways in use.
After an initially smooth approach, during which the A/T had been disengaged at about 2000 feet agl, turbulence had begun to increase below 1500 ft aal. The AP was disconnected just below 1000 feet aal and, after initially managing the flight path successfully, once below 400 feet aal the PF “experienced increasing difficulty controlling the aircraft” and made frequent use of full sidestick inputs. However, the approach had been continued and thrust set to flight idle at about 70 feet agl. Almost immediately a go around was then commenced but the engines had not had time to spool up from idle before the aircraft main gear briefly hit the runway and fully compressed before the aircraft climbed away. The repositioning to a second approach and the rest of the flight thereafter proceeded without further event.
The attitude of the aircraft at the time when the main gear touched the runway was found to have been just under 10º, similar to the commanded sidestick input. Airbus advised that the minimum attitude for a tail strike with the main gear fully extended was 11.2 º which confirmed that the tail strike had occurred during compression of the gear.
It was noted that after a tailwind component of 4 knots for most of the approach, a headwind component of 8 knots had prevailed from about 200 feet aal and this had then changed to a tailwind component of the same amount as the go around was initiated. The opinion of the aircraft manufacturer was that the commencement of a go around from a very low level with thrust at flight idle made a tail strike in the prevailing conditions “unavoidable”.
The concluding observation of the Investigation was as follows:
“The final sequence of events which lead to the tail strike appears to have been started with the change of relative wind experienced just before landing. This enhanced the aircraft’s performance and was probably the reason the co-pilot reduced thrust and applied a nose-down pitch input, at the same time as applying up to full lateral control inputs. The aircraft’s engines had quickly reduced to near idle rpm so the aircraft continued to sink despite the subsequently increasing pitch attitude, which may have accounted for the pilots’ impression that the aircraft had been subject to a sudden downdraft.”
The Final Report was published on 13 September 2012. No Safety Recommendations were made.