AW169 Birdstrike with a Turkey Vulture (N307TC of Travis County EMS STAR Flight)

On 22 November 2021, Leonardo AW169 air ambulance N307TC of STAR Flight (Travis County Emergency Medical Services) suffered a birdstrike from a Turkey Vulture near Austin, Texas.  The helicopter, which had six occupants, was inbound with a patient from Bastrop, Texas.  It was one of three STAR Flight introduced in 2019 as the US launch customer for the AW169 in HEMS operations.

The US National Transportation Safety Board (NTSBpublic docket, opened 19 April 2022 explains:

The medical crew member sitting in the front left cockpit seat, was the first to see the bird and announced its presence. The vulture was first seen ascending from the lower left field of view, it maintained its current track. It looked as though it was going to impact directly in the middle of the right front windshield.

As soon as {the Pilot-in-Command] PIC saw the vulture, he maneuvered the aircraft to the left and started to descend in an attempt to avoid the vulture or minimize the severity of the impact location on the aircraft. Seemingly, within a couple of seconds after maneuvering the bird impacted the aircraft.

PIC quickly determined that they needed to divert from the intended point of landing at Seton Main Hospital, and land at the STAR Flight Hangar Helipad (TE94) as it was just over 1 minute away. PIC felt that going to the STAR Flight hangar helipad was the most expeditious means to safely terminate the flight.

The aircraft landed safely with no injuries to the occupants.  When inspected on the ground the damage reportedly consisted of:

  • Cracked front right windshield
  • Cracked windshield support beam
  • Cracked greenhouse window
  • Undetermined main rotor blade surface damage.
Limited Birdstrike Damage to Travis County EMS (STARFlight) Leonardo AW169 Air Ambulance (Credit: via NRSB)

Limited Birdstrike Damage to Travis County EMS (STAR Flight) Leonardo AW169 Air Ambulance (Credit: via NRSB)

The AW169 certification basis is CS-29 Amendment 2, dated 17 November 2008.  This requires compliance with the following requirement:

CS 29.631 Birdstrike: The rotorcraft must be designed to assure capability of continued safe flight and landing (for Category A) or safe landing (for Category B) after impact with a 1 kg bird, when the velocity of the rotorcraft (relative to the bird along the flight path of the rotorcraft) is equal to VNE or VH (whichever is the lesser) at altitudes up to 2438 m (8 000 ft).

Compliance must be shown by tests, or by analysis based on tests carried out on sufficiently representative structures of similar design.

Turkey Vultures typically weigh 0.8 to 2.41 kg (1.8 to 5.3 lb) so this bird mass most likely exceeded the certification requirements.  The rotorcraft velocity at impact is not recorded for this impact.

In a presentation on behalf of the Rotorcraft Bird Strike Working Group (RBSWG) to the 11th EASA Rotorcraft Symposium  in December 2017 it was revealed that in the US 94% of the current helicopter fleet is made up of types that never needed to meet a birdstrike requirement.

CS 29.631 is harmonised with US certification requirements.  The AW169s nearest competitor only partially compliant with 29.631 (with the windscreens in particular being noted by the FAA as non-compliant, due to so-called grandfather rights).

Travis County HEMS  Leonardo AW169 at HeliExpo 2019 (Credit: Aerossurance)

Travis County HEMS Leonardo AW169 at HeliExpo 2019 (Credit: Aerossurance)

Safety Resources

The European Safety Promotion Network Rotorcraft (ESPN-R) has a helicopter safety discussion group on LinkedIn.

EASA have issued Safety Information Bulletin SIB 2021-07 on Bird Strike Risk Mitigation in Rotorcraft Operations and accompanying safety promotion material.

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