| Occurrence Briefs are concise reports that detail the facts surrounding a transport safety occurrence, as received in the initial notification and any follow-up enquiries. They provide an opportunity to share safety messages in the absence of an investigation. |
What happened
On 12 September 2020, the pilot of a Cessna 188 was conducting aerial application operations on a crop near Urana township, New South Wales. The pilot had just completed the final planned spray pass and, after observing a small amount of chemical remaining in the hopper, decided to spray the remainder in an extra pass. The selected run included two sets of known powerlines from the previous operation with a T-intersection running across the planned spray run (Figure 1). Another company aircraft was operating nearby and the pilot contacted them by radio to advise them of the change of plans and to organise separation. Approaching the run, the pilot identified the powerlines, and turned their attention to the other company aircraft to ensure separation for the run.
With their focus momentarily diverted, the pilot commenced an unplanned descent prior to the T-intersection in the wires. The pilot reported being aware of the crossing wire but did not observe the powerline prior to contact, striking the lines with the undercarriage gear legs. The wire-cutters fitted to the gear legs cut the first wire but were ineffective on the second wire with the aircraft decelerating rapidly and pitching towards the ground.
The aircraft collided with terrain in a level attitude, coming to rest in the paddock 70 m from the strike location and the pilot exited the aircraft uninjured. The aircraft was substantially damaged.
Figure 1: Flight path and powerline location
Source: Look up and live web application. Annotated by the ATSB.
Safety message
Wirestrikes pose an on-going hazard to aerial agricultural operations. Between 1 January 2015 and 12 September 2020, 154 wirestrike occurrences were reported to the Australian Transport Safety Bureau (ATSB). Of these, 102 strikes were recorded during aerial agricultural operations with 21 of the occurrences resulting in an accident. Previous research by the ATSB has shown that 63 per cent of pilots involved in a wirestrike accident were aware of the location of the wire before they struck it. (Aviation Research and Analysis Report – B2005/0055)
This accident highlights the dangers of distractions and last-minute change of plans, especially those made inflight during low-level operations. The ATSB has released, in association with the Aerial Agriculture Association of Australia, an educational booklet, Wirestrikes involving known wires: A manageable aerial agriculture hazard (AR-2011-028). This booklet contains numerous wirestrike accidents, the lessons learnt from them and suggestions to safely manage low-level flying Inflight decision making is one of the ATSB’s major safety concerns.
About this report
Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.