WEEK 22
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
Ground resonance during marine pilot transfer results in loss of control during heli-deck take-off.
WHAT?
An Agusta A109 was conducting a marine pilot transfer to a bulk carrier. After successfully delivering an inbound marine pilot to the vessel, the helicopter was taking off again when it developed severe vibrations. The crew lost control, and the aircraft crashed on deck, sustaining substantial damage. Both pilots and the ship’s crew escaped without serious injury.
WHERE?
Aboard bulk carrier Star Coral at the Blossom Bank marine pilot boarding ground, approximately 200 km north-east of Queensland, Australia.
WHEN?
Morning of 25 February 2025. ATSB report published 29 July 2025.
HOW?
Following an uneventful landing, the helicopter remained at flight idle on the ship’s helideck while the crew coordinated the next pilot transfer. Conditions were within the operator’s limits, with a 20–28 knot headwind and less than 2° of ship roll. As the pilot flying raised the collective and the helicopter became light on its landing gear, both pilots suddenly experienced severe vibrations. Believing the main rotor may have contacted the tail boom, the pilot in command assumed control without the standard verbal handover while the pilot flying continued attempting to lift the helicopter clear of the deck. The collective was lowered, the helicopter rebounded on the helideck, and the oscillations rapidly intensified until the cyclic became uncontrollable. The pilot in command shut down both engines, after which the helicopter came to rest upright after rotating more than 90°. The ATSB found no evidence of rotor strikes prior to the loss of control or any mechanical defects that would explain the occurrence.
CONDITIONS?
The operation was conducted from the helideck of a moving ship. Environmental conditions were within limits. The pilot flying was operating under the company’s Pilot In-Command Under Supervision (PICUS) program, having accumulated approximately 50 hours on type and with no prior experience in marine pilot transfer operations before joining the operator. The training captain had more than 10,000 flight hours, including 3,800 hours on the A109E. The 109’s fully articulated rotor system can make it susceptible to ground resonance if abnormal rotor and landing gear oscillations develop.
OUTCOME?
The helicopter sustained substantial damage, including separation of the tail rotor and major rotor system damage. Both pilots sustained minor bruising, but neither was seriously injured. No members of the ship’s crew were injured.
WHY?
The ATSB concluded that the helicopter most likely entered ground resonance during the initial stage of take-off, producing rapidly increasing vertical oscillations through the airframe. Although the precise trigger could not be determined, no evidence indicated that a mechanical fault or rotor strike initiated the event.
Investigators found that discontinuing the take-off probably aggravated the ground resonance and resulted in the subsequent loss of control. The pilot flying attempted to continue the take-off, while the supervising pilot -believing the helicopter had suffered a rotor strike- lowered the collective and assumed control without a formal transfer. This simultaneous but uncoordinated response reflected the extremely limited time available to react.
While the operator’s emergency procedures were considered adequate, they did not include specific guidance on ground resonance, nor did they require pre-flight briefing of pilot roles during an actual emergency on supervised training flights. Following the occurrence, the operator introduced dedicated ground resonance procedures, enhanced training materials, and revised briefing requirements to include command responsibility, transfer of control, emergency actions, and human factors considerations during two-pilot operations.
REFERENCE?
Australian Transport Safety Bureau. (2025). Loss of control during marine pilot transfer operations involving Agusta A109E, VH-XUM and bulk carrier Star Coral, about 200 km north-east of Mackay, Queensland, on 25 February 2025 (AO-2025-009). 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.
competentaviators.com 