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PC9, Manoeuvring, Warbelow Germany, 2012

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Summary
On 27 September 2012, a civil-operated Pilatus PC9 facilitating military target training for ground forces sustained structural damage to one wing when it struck an Osprey whilst at high speed and low level. The aircraft immediately became uncontrollable and the pilots did not have time to activate their ejector seats before the aircraft crashed and was destroyed. The Investigation noted that there were no relevant bird strike tolerance requirements for civil aircraft and attributed the accident systemically to use of such aircraft for target training and their operation at high speeds in airspace with a high bird strike risk.
Event Details
When September 2012
Actual or Potential
Event Type
Bird Strike, Loss of Control
Day/Night Day
Flight Conditions VMC
Flight Details
Aircraft PILATUS PC-9 Beech
Operator Private
Type of Flight Aerial Work
Origin Neubrandenburg Airport
Take off Commenced Yes
Flight Airborne Yes
Flight Completed No
Flight Phase Manoeuvring
MNV
BS
Tag(s) Large Birds,
Significant Airframe Damage
LOC
Tag(s) Airframe Structural Failure,
Bird or Animal Strike
Outcome
Damage or injury Yes
Aircraft damage Hull loss
Fatalities Most or all occupants (2)
Causal Factor Group(s)
Group(s) Aircraft Technical
Safety Recommendation(s)
Group(s) Aircraft Airworthiness
Investigation Type
Type Independent

Description

On 27 September 2012, the two pilot crew of a civil-registered Pilatus PC9/B being operated from Neubrandenburg airport by a private company under contract to the German Federal Armed Forces lost control of their aircraft whilst engaged in facilitation of target practice for ground forces in day VMC when it hit a medium sized bird at high speed and at low level. Control was not regained and the aircraft crashed and was destroyed nearby killing both pilots.

Investigation

An Investigation was carried out by the German Bundesstelle für Flugunfalluntersuchung (Germany) (BFU). The accident aircraft was not fitted with flight recorders - nor it was required to be, but the military authorities made their secondary radar recording available to the Investigation. The private company operating the aircraft specialised in conducting aerial target and test flights for military purposes within Germany and did not - and was not required to - hold an Air Operator Certificate.

It was found that the aircraft involved had been the trailing one in a 2-ship formation which had taken off from Neubrandenburg in order to transit to a military exercise area approximately 20 nm south east of the city of Rostock approximately 45 minutes prior to the crash. In accordance with normal practice, only the lead aircraft had been operating its transponder and communicating by R/T but its commander had confirmed to ATC that the aircraft would be remaining within half a mile of each other "most of the time".

Both flight crew of the accident aircraft, the 57 year-old commander and a 59 year-old second pilot, were, in line with most of those employed by the Operator, former military pilots. They had 1393 and 2052 hours respectively on type and both had flown between 250 and 300 hours on the type since the beginning of 2012.

After a 5 minute transit to the exercise area, the two aircraft began a series of approaches to the vicinity of the anti-aircraft forces on training. On the seventh of these, during the minute prior to the estimated time of the bird strike, the two aircraft were in the process of completing their seventh approach to the location of the personnel on training. The lead aircraft was recorded as having just descended to approximately 250 feet agl and then flying for 15 seconds at that height with a ground speed of approximately 270 knots before climbing to approximately 1800 feet agl in 36 seconds and then descending to 300 feet agl over 15 seconds before climbing away. Evidence from three military eye witnesses indicated that with both aircraft level, the trailing aircraft had turned to climb in the opposite direction to the leader but had then "pulled up briefly, rolled and then crashed". Another witness who had been in the forest area which the aircraft had been flying over had seen the trailing aircraft flying at a low altitude when "about five or six" ospreys, a species known to nest nearby, had flown into the path of the aircraft which hit one bird and then "fell toward the ground until it disappeared behind the forest".

Radio conversations between ground stations began immediately and the aircraft controller informed the formation leader about the reports of a crash and asked "…confirm that's a fake?" The formation leader, unaware of anything untoward at that point, tried - unsuccessfully - to establish radio contact and began to search. Seven minutes later, he located the crash site in an open field and communicated the location. The aircraft had been completely destroyed by impact forces. Subsequent examination of the wreckage and its disposition led to the conclusion that part of an osprey carcase found in the vicinity and weighing 1.26 kg may well have been from a bird which had impacted the left wing and led to part of it detaching in flight.

Unusually for a civil registered aircraft, ejection seats were installed in both pilot positions but although they could be operated between 60 and 400 knots and between 0 and 40,000 feet, neither had been operated and it was concluded that there had been insufficient time - less than 4 seconds - in which to achieve this.

The Investigation noted that the practice of contracting civil operators to fly in support of military target practice was well established, with the Joint Services Command being responsible for "the process management of the manned and unmanned aerial target demonstrations including planning, command, conduct, and supervision" of all such operations. The military authorities "stated that they had not issued any special certification for, or conducted any supervision, or analysis of the flight safety hazards" at the civil company which was operating the accident aircraft.

It was noted that the accident site was located close to a designated Aircraft Relevant Bird Area (ARA) which was marked on the 1:500,000 topographical chart for the area.

The Investigation drew a clear distinction between 'normal' VFR flight operations and the detail which the accident aircraft had been helping to fulfil, concluding that "the flight profile corresponded with that of military aircraft". At the time of the bird strike, it was noted that the aircraft had been at "a very low altitude and therefore in an altitude in which most bird strikes occur" and that "compared to other civil aircraft, the aircraft flew in this low altitude with a very high speed". Such a high speed in conjunction with the likely mass of the bird would have led to a correspondingly high energy impact - estimated as equivalent to at least 14,000 Joules and therefore conducive to a high degree of destruction. In this respect, it was noted that civil-registered aircraft certified in accordance with FAR/JAR/CS 23 "have a significant(ly) lower bird strike tolerance compared to fighter jets".

The Causes of the Accident were formally stated as follows:

Immediate Causes:

  • The airplane's wing was severely damaged by a bird strike. This resulted in a faulty lift distribution and aileron control failure which subsequently led to loss of control.
  • Due to the low altitude and the rapid roll movement the time was not sufficient to activate the ejection seats.

Systemic Causes:

  • Flight in an altitude with high bird concentration
  • Flight with high speeds
  • Use of CS-23 airplanes in military flight profiles

One Safety Recommendation was issued as a result of the Investigation as follows:

  • that the Luftfahrtamt der Bundeswehr (LufABw) (Military Aviation Authority) should ensure that companies acting as civil contracting partners for the Bundeswehr conducting aerial target demonstrations, meet the highest Bundeswehr standards in regard to their flight operations and flight safety organisations.
If the civil contracting partner does not hold an Air Operator Certificate (AOC) issued by a Civil Aviation Authority, the LufABw should ensure that the civil contracting partner is organised such that hazard analyses are conducted in regard to their aerial target demonstrations operations which are suited to ensure a high degree of operational safety.
If the civil contracting partner is a Civil Air Operator certified by the Luftfahrt-Bundesamt (LBA), regular information exchange should take place between the LufABw and the LBA in regard to special operational and flight safety issues in order to support the LBA. (05/2015)

The Final Report was completed on 13 August 2015.

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