H2F Weekly Mayday #26

WEEK 26

H2F brings you the ‘helicopter mayday of the week’ with a short accident report summary. I tell you what happened. You think more about why it happened. We all learn from it. Because that’s what accident reporting is for.

TITLE

Loss of control during night offshore HEMS flight.

WHAT?

A Bell 407 was tasked to collect a patient with a fractured leg and possible neck injuries for transfer to hospital. It departed under night VFR with a crew of single pilot, crewman and paramedic. About 12 minutes after departure, a radar trace showed a series of significant heading and altitude changes before the helicopter entered an extreme descent and impacted the sea. The ATSB could not conclusively establish what initiated the loss of control but considered pilot disorientation the most likely explanation.

WHERE?

Queensland, Australia while flying from Mackay toward Hamilton Island. The route took the aircraft offshore over the Coral Sea on a dark night with no visual references or cultural lighting available from land.

WHEN?

17 October 2003. The ATSB final report was published in March 2005.

HOW?

After departure, the helicopter climbed to about 3,000 ft and initially tracked toward Hamilton Island. During the final minute recorded by radar, it began a series of substantial turns and altitude changes, including turns toward and away from the mainland, climbing to 3,800 ft before making large heading changes and ending in a rapid descent and impact with the water. No distress transmission was received. Examination of the wreckage did not identify any mechanical failure likely to have contributed to the accident.

CONDITIONS?

The flight was conducted on a dark night over water, with no cultural lighting or discernible horizon. Cloud was forecast around the altitude being flown and could have obscured the limited celestial illumination available. Consequently, the pilot had few external visual cues with which to maintain attitude. The Bell 407 was not equipped for or approved for IFR flight and the pilot did not hold an instrument rating. He had limited instrument-flying experience but was also relatively inexperienced on the Bell 407 and in night operations over water beyond sight of land. He was also new to both the organisation and EMS operations.

OUTCOME?

The helicopter struck the sea at high speed and was destroyed. The pilot, crewman and paramedic were fatally injured. Personnel at Hamilton Island queried the helicopter’s whereabouts about 35 minutes after departure, initiating unsuccessful attempts to contact it. Search crews subsequently located floating wreckage.

WHY?

The investigation could not determine with certainty why the helicopter departed controlled flight. However, the circumstances were consistent with pilot spatial disorientation and loss of control in dark-night conditions. Importantly, investigators identified a much broader combination of recognised human factors risks associated with both HEMS and offshore flight:

• The dark, featureless ocean environment provided no visible horizon or surface lighting, while cloud potentially further reduced celestial illumination, creating conditions conducive to spatial disorientation.
• The Bell 407 had been accepted for the EMS contract despite an independent evaluation identifying limitations associated with its lack of equipment for IFR operations and mitigation of night-VFR risk. The investigators noted that cost may also have influenced the procurement decision.
• Actual or perceived pressure not to reject the mission because of weather or other reasons may have existed within the operating environment, alongside an apparent lack of appreciation of risks and the limitations of night VFR offshore helicopter operations. Further to the organizational risk the pilot was new to the operation which could have increased perceived pressure to achieve the task.
• The pilot’s limited instrument experience, absence of an instrument rating, relatively low experience on type and limited experience conducting extended over-water night operations significantly increased the risks associated and left reduced capability to manage a loss of external visual references.
• The EMS system at the time involved multiple organisations with divided safety responsibilities, with no single aviation organisation exercising overall operational safety oversight. The investigation considered that this had the potential to diffuse safety accountability.

REFERENCE?

Australian Transport Safety Bureau. (2005). Bell 407 VH-HTD, Cape Hillsborough, Queensland, 17 October 2003 (Aviation Safety Investigation Report 200304282). Australian Transport Safety Bureau.

Note:

Accident reports selected from the following open source databases: US NTSB; UK AAIB; Flight Safety Foundation’s Aviation Safety Network; Australia’s ATSB. Ireland’s AAIU; Taiwan’s TTSB; France’s BEA; Spain’s CIAIAC. Germany’s BFU.