External flood light configuration in night winch capable helicopters

Section 21 (2) of the Transport Safety Investigation Act 2003 (TSI Act) empowers the Australian Transport Safety Bureau (ATSB) to discontinue an investigation into a transport safety matter at any time. Section 21 (3) of the TSI Act requires the ATSB to publish a statement setting out the reasons for discontinuing an investigation.

On 24 December 2011 an Agusta Westland AW139 helicopter departed Bankstown Airport to retrieve a seriously injured patient in the Budderoo National Park, about 16 km west-south-west of Wollongong Airport, New South Wales. During the retrieval, the patient and one of the paramedics hit rocks at the base of the waterfall. The paramedic died from the impact. The ATSB investigation (AO-2011-166) identified four safety issues, including the following:

The helicopter’s lighting set-up did not allow independent control of the searchlights by the pilot using the switches on the flight controls, as required by the operations manual and Civil Aviation Order [CAO] 29.11, and increased the risk of loss of hover reference and distraction in the case of a single light failure or switch miss-selection by a pilot.

The relevant section of the CAO 29.11 sub section 6.3 stated:

A helicopter shall not engage in winching and/or rappelling operations over the land at night unless it is equipped…

(b) as specified in Appendix V of section 20.18 with the addition of…

(ii)    2 white lights operable by the pilot and trainable in azimuth and elevation without removing his/her hands from the flying controls…

Note:   A single white light having 2 separately energized filaments may be approved as meeting this requirement provided that the selection of the alternative light can be accomplished by the pilot without removing his/her hands from the flying controls.

In order to ascertain the extent of the lighting-related safety issue, on 1 May 2013 a safety issues investigation was commenced under the TSI Act. This included the development of a questionnaire that was sent to 10 helicopter operators who were capable of night winching operations. Those operators represented about two thirds of the night winch-capable operators throughout Australia with a combined total of 89 winch-capable helicopters of various types.

The answers to the survey from the 10 operators indicated that about 50 per cent fully complied with CAO 29.11. Of those who did not comply, most believed that they did comply due to their interpretation of the CAO. In all non-compliance situations the pilot had to move their hand from the collective in order to switch between light controls. From that point on the selected light could be controlled from the collective. All respondents believed that the lighting on their helicopters was adequate.

The Civil Aviation Safety Authority (CASA) was made aware of these findings. CASA advised that it realised it could be difficult to comply with the existing CAO 29.11 requirement and that it was proposing to modify the requirements of the CAO. This modification would require the helicopter to only be fitted with one light that could be operated by a pilot without removing their hands form the flying controls.[1]

The likelihood of a lighting failure leading to a substantial loss of hover reference during night winching operations, which are increasingly employing night vision devices, is very low. The ATSB also recognises that CAO 29.11 is being changed to make it easier to comply, and that forcing operators to comply with the existing requirement may introduce additional risks given the design difficulties involved.

Based on the feedback provided by night winch-capable helicopter operators and CASA, the ATSB assessed that the lighting issue did not appear to form a significant safety issue for ongoing helicopter night winching operations. On that basis, the ATSB has decided to discontinue its investigation.