WEEK 21
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
Collision with tree during take-off from a confined site.
WHAT?
An AS350 departed a private Helicopter Landing Site (HLS). Shortly after lifting into a vertical climb, the main rotor struck tree branches approximately 19 m above the ground. The impact separated the tail boom, resulting in loss of control and ground impact. Both occupants were fatally injured and the helicopter was destroyed.
WHERE?
Touques, Calvados, France.
WHEN?
7 March 2021.
HOW?
The helicopter departed vertically from a confined area. The take-off profile provided only a small clearance from nearby trees. During the climb, the main rotor contacted branches that were difficult to distinguish against the shaded background. The rotor strike caused structural failure, including separation of the tail boom, leading to an unrecoverable loss of control and impact with the ground approximately 50 m from the take-off point. The helicopter was producing normal engine power until the rotor strike, with no evidence of mechanical malfunction.
CONDITIONS?
Daylight VMC with good visibility (>10 km).
Light northeasterly winds (5–10 kt).
Low sun angle created shaded conditions and poor contrast around nearby obstacles.
The helicopter was within weight and balance limits and had sufficient power for a vertical take-off.
The confined HLS contained trees and terrain slope limitations that restricted manoeuvring options.
OUTCOME?
The pilot and passenger sustained fatal injuries. The helicopter was destroyed. The investigation determined that no aircraft system or engine failure contributed to the accident.
WHY?
Investigators concluded that the accident resulted from the rotor blades striking a tree during a vertical take-off with inadequate obstacle clearance. Several interacting human and organisational factors reduced the safety margin:
There were no established criteria defining safe obstacle clearance distances for confined-area operations or training, reducing available safety guidance.
The landing position chosen the previous day limited safe departure options and effectively committed the pilot to a vertical departure close to obstacles.
Tree branches were located in shadow, making distance estimation difficult due to reduced visual contrast.
The pilot was not wearing the required corrective lenses, likely degrading visual performance.
Age-related reduction in contrast sensitivity may have further impaired obstacle detection.
Investigators could not determine who was manipulating the controls because evidence suggested the passenger may have been receiving helicopter instruction outside an approved training organisation. This informal training arrangement may have lacked the structured progression and risk management provided by an approved training organisation.
This accident demonstrates how several individually manageable human factors can align to create a fatal outcome. Reduced visual contrast, age-related changes in vision, failure to wear prescribed corrective lenses, accepting limited safety margins during confined-area operations, and informal training practices collectively eroded the pilot’s ability to detect hazards and maintain safe obstacle clearance.
REFERENCE?
Bureau d’Enquêtes et d’Analyses pour la Sécurité de l’Aviation Civile. (2022). Investigation report BEA2021-0089: Accident to the Airbus AS350 B, F-GIBM, on 7 March 2021 at Touques (Calvados). BEA.
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 