Investigation Findings

Investigation Findings

The following is a selection and summary of analysis and findings from the TAIC report into this accident, 03-001. The full report can be found here and is free to download from the TAIC website here.

III damage 2The weather was obviously a factor, because the collision with the trees occurred while the pilot was climbing the helicopter through cloud as a result of a deliberate emergency decision. Her decision followed the realisation she had inadvertently overflown a waypoint and was heading into an area of higher terrain.

The overflying of the waypoint probably resulted from a number of factors, including these:

  • The local weather had deteriorated;
  • The pilot had some difficulty reading the GPS information;
  • There were no ground lights in that sector, and the terrain was naturally indistinct at night;
  • The successive waypoints were close together on that part of the route; only about 30 seconds, and about 60 seconds flying time apart respectively;
  • It was a good idea to use the crewman to read out the GPS, but it may have been called for too late;
  • The approach to the waypoint was on a northerly rather than a northeast heading, after the small deviation she had made, and any visual cues (such as ground lights seen through the Tauherenikau Gorge) would have been slightly behind, rather than in her two o’clock position.

The pilot’s pre-flight assessment of the weather information and her flight planning were significant factors in the accident. The GAWX did not specifically predict lower cloud with poor visibility on the eastern side of the ranges compared with Hutt Valley and Wellington, but some appreciation of orographic weather with the southerly airflow might have alerted her to that probability.

The selection of an altitude of 2500 feet for the route did not take into account the location of higher terrain close to the route, and the need to fly safely above it to allow for any navigational inaccuracies on the way. A consideration of high terrain within 5 NM either side of the track might have led to a conclusion that a minimum safe altitude for this route under night VFR was probably close to 5000 feet.

III crash site2The indication from the Skymaster log showed the pilot had overflown the Tauherenikau River waypoint by about 20 seconds, or 0.4 NM. This small navigational overshoot effectively put the flight into danger. Such a small margin may be acceptable by day, with good light and visibility, but was insufficient on this night, with the prevailing low illumination and decreased visibility.

The pilot’s action, in deciding to climb as soon as she realised they were in danger after overflying the waypoint was appropriate and, along with her reaction to the radio altimeter alert of pitching the helicopter nose-up, was fortuitous in allowing the helicopter to avoid a major impact with the ground. Any such terrain avoidance manoeuvre should be assertively flown to achieve maximum climb angle for best effect. The alternative, of making a 180° turn to backtrack, may not have been a safe option, given her position, which was unknown in relation to high terrain.

The pilot’s actions after the collision were appropriate and successful. They consisted of a recovery, on instruments, to normal flight from an unusual attitude and very low airspeed; continuing to climb the helicopter on a suitable heading until visual contact was regained; flying to Masterton aerodrome; devising a plan; and hovering for nearly 1.5 hours until she could land the helicopter on the bed of tyres. Her flying the damaged helicopter to a successful emergency landing, with her injured hand, was a significant achievement.

The AIA’s action in developing standards and requirements for helicopter VFR air ambulance and search and rescue night operations was a positive initiative, and indicates a general industry realisation that night VFR operations need prescriptions and guidelines, in addition to the Civil Aviation Rules. Standards developed by experienced pilots and operational managers are likely to be practical and relevant, so should be encouraged to facilitate widespread adoption.

TAIC recommended the CAA could do more to ensure that air operators providing night VFR flights set and apply appropriate operational standards. While the regulatory minima are necessary, operators should also have guidance material in their operation manuals, and pilot training and checking to ensure that their methods are consistent and appropriate to what they do. A recommendation was made to the Director of Civil Aviation that he ensures operators include relevant operational material for their night VFR flights in their expositions.

As recommended by TAIC, a Night VFR GAP booklet was produced in response to this accident.

TAIC Findings

These are the exact findings from the TAIC Accident Report. The full report can be viewed here.

  • The pilot was appropriately licensed, experienced and fit to conduct the flight.
  • The helicopter had a valid Airworthiness Certificate, and had been appropriately maintained.
  • The helicopter was being flown on a company route not normally used at night, at an altitude which provided an insufficient safety margin above terrain for night VFR operations.
  • A small navigational error resulted in the pilot making an appropriate emergency climb through cloud, during which the helicopter collided with trees but continued flying.
  • The pilot’s actions after the collision were appropriate, and resulted in a safe emergency landing.
  • The operator did not provide additional relevant guidance for its pilot on night VFR operations.
  • CAA could do more to ensure that air operators providing night VFR flights set and apply appropriate operational standards.
  • There was a lack of guidance material for private cross-country operations under night VFR.