Aviation safety investigations & reports

Loss of control and collision with terrain involving Eurocopter AS350BA helicopter VH-BAA, Hobart Airport, Tasmania, on 7 November 2017

Investigation number:
AO-2017-109
Status: Completed
Investigation completed
Phase: Final report: Dissemination Read more information on this investigation phase

Final Report

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What happened

On 7 November 2017, a chief flying instructor (CFI) and pilot under instruction (PUI) were flying a Eurocopter AS350BA Squirrel, registered VH-BAA. They were conducting practice emergencies under visual flight rules at Hobart Airport, Tasmania. During hydraulic system failure practice, control of the helicopter was lost and the aircraft collided with terrain. The CFI was fatally injured and the PUI was seriously injured.

What the ATSB found

Flight manual emergency procedures stipulate that in order to maintain control following a hydraulic system failure (or simulated failure), a shallow approach should be made into wind and the helicopter should not enter a hover. On this occasion, the aircraft approached crosswind and came to a high hover without hydraulic assistance. Consequently, the helicopter was rendered uncontrollable. A delay in restoration of the hydraulic system prevented the crew from regaining control before collision with terrain.

The ATSB also identified that:

  • An intermittent fault in the hydraulic cut-off switch may have delayed restoration of flight control hydraulic pressure.
  • A pre‑flight brief was not conducted between the CFI and PUI which may have led to confusion over aircraft control and delayed restoration of the hydraulic system.

Due to a lack of available information, the influence, if any, of these two factors on the accident sequence could not be determined.

What's been done as a result

Following this accident, the operator:

  • employed a trained and regulator-approved safety manager
  • updated the training school operations manual with stricter controls on performing AS350 sequences as per the flight manual requirements
  • installed an electronic system for tracking competencies and currencies.

The operator has also separated key roles of chief executive officer, chief flight instructor and the head of flight operations, which were previously conducted solely by the chief flight instructor.

Safety message

Compliance with the AS350 flight manual requirements following a real or simulated hydraulic failure ensures that the helicopter remains controllable during all phases of flight.

As this, and many other similar accidents illustrate, hovering an AS350 without hydraulic assistance can lead to a rapid, catastrophic loss of control even for highly experienced pilots. The Royal Australian Air Force found in evaluation of the AS350, while hovering without hydraulics, that the AS350 is subject to random perturbations, and reduction in control authority. Additionally the AS350 flight manual notes that without hydraulics the helicopter is subject to rapid changes in control direction and force.

In a training context, the rapid development of this accident, reinforces the need for a clear understanding and coordination between instructor and student when conducting hazardous activities such as simulated system failures.

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The occurrence

Context

Safety analysis

Findings

Sources and submissions

Appendix A

Appendix B

Preliminary report

Preliminary report

Published: 18 December 2017

At about 1635 Eastern Daylight‑saving Time[1] 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.

Figure 1: Approximate flight path of the helicopter (not to scale), showing the approach to the X-Ray training area, where the helicopter slowed before making an abrupt left turn and impacting terrain.

Figure 1: Approximate flight path of the helicopter (not to scale), showing the approach to the X-Ray training area, where the helicopter slowed before making an abrupt left turn and impacting terrain.

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[2] (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).

Figure 2: Damage to the helicopter showing significant impact damage to the cockpit area and left landing skid tip, consistent with a left nose-down attitude on impact.

Figure 2: Damage to the helicopter showing significant impact damage to the cockpit area and left landing skid tip, consistent with a left nose-down attitude on impact.
Source: ATSB

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.

__________

  1. Eastern Daylightsaving Time was Coordinated Universal Time (UTC) + 11 hours.
  2. A landing conducted without establishing the helicopter in a hover.
General details
Date: 07 November 2017   Investigation status: Completed  
Time: 1722 EDT   Investigation level: Defined - click for an explanation of investigation levels  
Location   (show map): Hobart Airport   Investigation phase: Final report: Dissemination  
State: Tasmania   Occurrence type: Loss of control  
Release date: 22 July 2020   Occurrence category: Accident  
Report status: Final   Highest injury level: Fatal  

Aircraft details

Aircraft details
Aircraft manufacturer Aerospatiale Industries  
Aircraft model AS.350BA  
Aircraft registration VH-BAA  
Serial number 2015  
Operator Rotorlift Aviation  
Type of operation Flying Training  
Sector Helicopter  
Damage to aircraft Destroyed  
Departure point Hobart, Tasmania  
Destination Hobart, Tasmania  
Last update 22 July 2020