Turbulence Avoidance
A pilot encountered turbulence after deviating 5 NM right of track, ending up 10 NM from a weather cell. The operations manual advised a 20 NM separation from such weather phenomena. A previous ATSB investigation report indicated that a 10 NM separation might not be sufficient, and a recent seminar reiterated this guidance. However, the pilot missed these recent reminders, partly due to the realities of remote area operations. Although the loss of control was unexpected, some turbulence could have been reasonably foreseen given the proximity.
The pilot was secured with a harness, but the passengers and cabin were not adequately prepared. The pre-flight briefing instructed that seatbelts be worn at all times and be tight, and the pilot visually checked before departure. However, when turbulence is anticipated or encountered, these instructions should be repeated with an order to stow loose items. In this case, the pilot could not communicate with passengers via intercom while airborne, limiting the ability to prepare the cabin.
Post-Incident Reporting
A loss of control due to weather is an immediately reportable matter for air transport operations under Regulation 2.3(3)(s) of the Transport Safety Investigation Act 2003. According to section 18 of the Act, the occurrence must be reported as soon as reasonably practicable to the ATSB by telephone, with a follow-up written report within 72 hours. All responsible persons with knowledge of the occurrence must ensure the report is made.
The pilot did not report the turbulence encounter to the operator until after the last flight of the day. Subsequently, both the pilot and operator had a responsibility to report to the ATSB. The operator reported the encounter 7 days after it occurred. Timely reporting is important for preserving perishable evidence.
Operational Support and Risk Management
During the turbulence encounter and loss of control, the pilot was certain that no airframe limitations were exceeded. If limitations were not exceeded, the pilot was not legally required to cease operations in that aircraft. However, in high turbulence, aircraft instruments may not provide an accurate picture of stress on the airframe, and it was reasonable to assume limits could have been exceeded.
Without formal guidance on steps after severe turbulence, the pilot did not report the incident or seek external input for decision-making. The pilot conducted a suboptimal inspection under the circumstances, recognizing potential damage and inspecting the aircraft to the extent possible for a pilot. Licensed aircraft maintenance engineers are qualified to inspect for abnormal flight loads, but the pilot did not consider such an inspection necessary. Although a later engineering inspection found no defects, continuing the flight without an appropriate inspection exposed the pilot, operator, and passengers to additional, avoidable risk.
The operator demonstrated active risk management by grounding the aircraft to ensure airworthiness after receiving the report. This set a visible benchmark of risk tolerance, which, if supported by formal guidelines, would clearly set operator expectations for pilots.
Even in remote areas, pilots are not expected to manage safety alone; facilities exist to enlist support and find alternative solutions. Operators should ensure well-communicated, structured solutions are in place. Reporting issues early allows operators to develop alternative solutions for customers, reducing operational pressure on pilots and supporting cautious decision-making. Passenger debriefing is another tool to help pilots and passengers process the occurrence and develop strategies for future avoidance.