Update: 7 November 2019
The investigation into the collision with terrain involving an AS350BA Squirrel helicopter, VH-BAA, at Hobart Airport, Tasmania, on 7 November 2017 is nearing completion.
ATSB investigators have so far gathered and analysed numerous information sources including:
- the conduct of training operations;
- the environment in which the occurrence flight took place;
- the systems of the helicopter pertinent to the event;
- changes to flight manual limitations;
- communication of flight manual limitations; and
- worldwide accident reports involving AS350 hydraulic failure.
The investigation team has tested a series of hypotheses to arrive at a number of safety factors that either contributed to the accident, or otherwise increased safety risk.
These hypotheses are now undergoing a Safety Factor Review with the ATSB’s directors of transport safety. This is a rigorous internal review of the progress of the investigation, its preliminary findings and focus.
The Safety Factor Review involves the investigation team presenting their evidence and analysis to reach consensus on the investigation findings. Once consensus is achieved, the report drafting phase of the investigation will begin.
Currently, the anticipated completion and publication release date of the final report is during the first quarter of 2020.
Published: 18 December 2017
At about 1635 Eastern Daylight‑saving Time on 7 November 2017, a Eurocopter AS350BA (AS350) helicopter, registered VH-BAA, departed Hobart Airport, Tasmania for a local training area to the northeast. On board were a pilot and instructor and the flight was the third training flight of an AS350 helicopter-type endorsement for the pilot.
The endorsement training was conducted over a two-day period. It included ground school training, and three flights that formed the practical component of the training syllabus. One instructor had assessed the first two flights but, since the third focussed on emergency procedure training, the occurrence instructor elected to fly with the pilot.
The pilot held a Commercial Pilot (Helicopter) Licence and a valid Class 1 Aviation Medical Certificate. The pilot had experience flying other turbine helicopter types, on various types of operations. The pilot’s existing low-level and sling approvals, which were reportedly held on a foreign licence, were also to be assessed during the AS350 type endorsement.
Following arrival in the training area, the pilot’s general helicopter handling and low-level flight were assessed. At about 1715, the pilots reported to air traffic control that operations in the training area were complete and requested a clearance back into the Hobart Airport control zone, to conduct practice emergencies. The approach to the airport reportedly involved conducting a simulated hydraulic system failure to the helicopter training area X-Ray (Figure 1).
Training Area X-Ray was located adjacent to and west of the main runway and was familiar to the pilot, as this area was used in the previous day’s training.
Source: Airservices Australia, modified by ATSB
The instructor reportedly announced the simulated failure to the pilot just prior to commencing the approach. The pilot responded to the simulated failure by stabilising the helicopter and reducing the airspeed to about 60 kt, in accordance with the manufacturer’s hydraulic failure procedure detailed in the aircraft’s flight manual.
The flight manual emphasised that, without hydraulic assistance, the flight controls exhibited force feedback requiring the pilot to exert additional force on the controls to maintain 60 kt in level flight. The manual also stated that, after transitioning to the recommended safety speed range, the second phase of the hydraulic failure procedure was to transition to slow run‑on landing (at around 10 kt) via a flat final approach in to the wind. The pilot reported that, as the helicopter decelerated and descended towards the landing area, they noted the additional control forces required.
A video camera installed at the airport recorded footage of the helicopter’s final approach. As the helicopter descended toward training area X-Ray, it initially appeared to be controlled and in a flatter than normal approach profile. The helicopter then appeared to slow into a high hover about 30 ft above the ground. Seconds later, it commenced an abrupt nose-down turn to the left and impacted the ground.
The training procedure section of the helicopter flight manual cautioned pilots to:
…not attempt to carry out hover flight or any low speed manoeuvre without hydraulic pressure assistance. The intensity and direction of the control feedback forces will change rapidly. This will result in excessive pilot workload, poor aircraft control, and possible loss of control.
The impact forces caused significant damage to the cockpit area, particularly the left pilot side (Figure 2).
Seated on the left side, the instructor sustained fatal injuries, while the pilot seated on the right was seriously injured.
The investigation is continuing, and will analyse the evidence obtained during the on-site investigation phase. Additional work will include a review of the:
- conduct of training operations
- helicopter systems
- any environmental influences that may have affected the operation of the helicopter at the time of the accident.
The information contained in this web update is released in accordance with section 25 of the Transport Safety Investigation Act 2003 and is derived from the initial investigation of the occurrence. Readers are cautioned that new evidence will become available as the investigation progresses that will enhance the ATSB's understanding of the accident as outlined in this web update. As such, no analysis or findings are included in this update.
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|Date:||07 November 2017||Investigation status:||Active|
|Time:||17:20 ESuT||Investigation level:||Defined - click for an explanation of investigation levels|
|Location:||Hobart Airport||Investigation phase:||Final report: Drafting|
|State:||Tasmania||Occurrence type:||Collision with terrain|
|Release date:||18 December 2017||Occurrence category:||Accident|
|Report status:||Preliminary||Highest injury level:||Fatal|
|Anticipated completion:||1st Quarter 2020|
|Aircraft manufacturer||Aerospatiale Industries|
|Damage to aircraft||Destroyed|
|Departure point||Hobart, Tasmania|