| 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. Because occurrence briefs are not investigations under the Transport Safety Investigation Act 2003, the information in them is de-identified. |
What happened
On 8 February 2024, a Bell Helicopter 47G-5A was being operated on a ferry flight between Katherine, Northern Territory, and Kununurra, Western Australia. The pilot was the sole person on board. At around 1545 local time, while in cruise approximately 30 NM (56 km) east‑north‑east of East Kimberley Regional Airport, the pilot noticed that the engine was running rough.
A smell of hot oil entered the cockpit, and the pilot elected to make a precautionary landing even though the cockpit instruments indicated no problems ‑ the oil pressure, oil temperature, and cylinder head temperature all remained within normal operating limits. Having identified a small clearing in remote, undulating terrain, the pilot landed before securing and exiting the helicopter to inspect the engine. The pilot identified oil dripping onto the exhaust creating smoke and that part of the exhaust from the middle cylinder had broken off at the manifold.
Due to the remote location, the pilot had no mobile or radio reception with which to send and receive communications. Additionally, the Emergency Position Indicating Radio Beacon (EPIRB) had been removed from the incident helicopter several days earlier. However, the pilot had nominated a SARTIME[1] for their arrival at the East Kimberley Regional Airport and knew that if the helicopter had not arrived by that time, it would trigger a search and rescue (SAR) response. At the time, the pilot was unaware that the operator could also access their track on OzRunways, which would have given the pilot greater confidence in being found once the SARTIME had passed.
Consequently, the pilot decided to troubleshoot the engine to assess its airworthiness. The pilot checked the oil level and found no obvious source of the observed leak or a discernible reduction in quantity. They then restarted the helicopter’s engine, hovering at a height sufficient to stay out of ground effect,[2] to conduct a power test. Although the helicopter was relatively light, the pilot noted an RPM drop and vibration as the helicopter climbed and consequently chose to land and shut down the engine for a second time in the same location. Upon checking the oil levels again, the pilot did not identify any further loss of quantity.
At approximately 1615, the pilot marked their exact location in their OzRunways electronic flight bag and composed a message on the operator’s internal group chat on a messaging application on their mobile phone. They then left the landing site on foot to attempt to obtain mobile phone reception. The pilot anticipated that if they obtained reception while they were walking, the message would automatically send. However, despite climbing the surrounding ridge and walking along higher ground towards the closest town of Kununurra, they were unable to establish any connection to the local phone network and returned to the helicopter.
The pilot then made a series of MAYDAY broadcasts on 3 different frequencies hoping to contact an overflying aircraft or Brisbane. These radio calls elicited no response except for one unclear transmission, and the pilot became increasingly concerned with the situation. At this point, they decided to restart the helicopter to climb to a sufficient (albeit low) altitude from which radio communications could be re‑established.
Although the pilot was able to restart the engine and position the helicopter into a hover, they quickly realised the altitude could not be maintained and landed the helicopter a third time at around 1735. During this landing sequence, at approximately 2 ft off the ground, the pilot reported hearing a ‘pop’ sound from the engine and noticed an accompanying further loss of power. The helicopter was landed successfully and shutdown, with no reported injuries or damage to the helicopter.
With sunset expected at approximately 1915, the pilot secured the helicopter in expectation of staying overnight at that location, and continued to make Mayday calls on all 3 frequencies. Just after 1830, a Robinson R22 (R22) helicopter flew over the incident site. The pilot of the R22 sighted the helicopter and landed nearby. The pilot of the R22 then took off and remained overhead while directing a larger Robinson R44 (R44) to the site. The pilot of the Bell 47G boarded the R44 and was taken to East Kimberley Regional Airport, arriving at around 1915.
Safety message
This incident highlights the importance of carrying appropriate communications equipment while conducting remote area operations. An Emergency Position Indicating Radio Beacon (EPIRB) is a device that can be activated to alert emergency services of the location of a person or vehicle in distress. Whether attached to the aircraft or carried by pilots, EPIRBs can enhance safety in remote operations.
A satellite phone also enables reliable communication with emergency services when pilots are operating in remote terrain. This can be particularly important in abnormal or emergency situations, as the geography of the landing area may block VHF transmissions (which operate largely on a line‑of‑sight basis) even if the aircraft radios are functioning and tuned to the appropriate local frequencies. In addition, mobile phones are generally reliant upon cellular network coverage, which may not sufficiently cover all remote areas. Of note, newer models of the iPhone from the iPhone 14 onwards now have an Emergency SOS via satellite feature that can connect users to emergency services via satellites when outside of cellular range.
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.
[1] SARTIME is an abbreviation for ‘time search action required’. A SARTIME is the time nominated by a pilot for the initiation of Search and Rescue (SAR) action.
[2] Out of ground effect: helicopters require less power to hover when in ‘ground effect’ then when out of ‘ground effect’ due to the cushioning effect created by the main rotor downwash striking the ground. The height of ‘ground effect’ is usually defined as more than one main rotor diameter above the surface.