WEEK 23
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
Impact with trees during go-around manoeuvre in brownout conditions
WHAT?
An AW139 operating an emergency medical service (HEMS) mission for Portugal’s National Institute of Medical Emergency (INEM) attempted to land at a quarry to evacuate an injured worker. During the final approach, the helicopter encountered severe brownout conditions caused by dust from the quarry. While attempting a go-around after losing visual references, the main rotor struck nearby trees before the helicopter crashed onto a slope. The helicopter sustained substantial damage, although all four occupants survived.
WHERE?
Near Atei, Mondim de Basto, Portugal.
WHEN?
2 September 2024. The GPIAAF published its final report on 22 July 2026.
HOW?
The crew accepted a HEMS mission to retrieve an injured quarry worker. During the flight, the emergency dispatch centre supplied coordinates in a format incompatible with the helicopter’s Flight Management System, initially leading the crew to the wrong quarry. After locating the correct site, they opted for an alternative landing area to avoid nearby buildings and briefed an escape route in anticipation of brownout. During the final descent, dust rapidly obscured all external visual references. The captain called for a go-around, but moments later the main rotor struck surrounding trees and the helicopter crashed onto the adjacent slope. Investigators found no evidence of mechanical malfunction.
CONDITIONS?
Conducted in day VMC, with the first officer acting as Pilot Flying under Pilot-in-Command Under Supervision (PICUS) and the captain serving as supervising Pilot Monitoring, a crew dynamic subsequently identified in the report to be a significant contributing factor, with the PF having greater experience on type. The landing site was an active quarry containing large quantities of fine dust capable of producing severe brownout. Although the crew recognised the hazard during their briefing, they continued the approach. An alternative landing site had been prepared by emergency responders but this information was never passed to the crew.
OUTCOME?
The helicopter sustained substantial damage after impacting trees and the ground. Neither pilot was injured, the nurse escaped unhurt, and the doctor sustained a minor knee injury.
WHY?
The investigation concluded that the accident resulted from the helicopter colliding with trees during an unsuccessful go-around after entering brownout conditions. Contributing factors included:
Loss of situational awareness after both pilots lost external visual references in brownout conditions.
The decision to continue the landing despite recognising the high risk of brownout.
Delayed initiation of the go-around and incorrect execution of the manoeuvre by the Pilot Flying.
A breakdown in CRM during the critical final approach. The supervising captain did not intervene early enough to discontinue the approach, while the PICUS pilot continued to rely on supervision after visual references had been lost, delaying decisive command action.
Limited operator training and awareness of brownout hazards and recovery techniques.
Poor coordination with emergency responders, including the failure to communicate the availability of a prepared alternative landing site.
Operational workload increased by inaccurate mission coordinates that delayed identification of the correct landing area and required manual navigation
REFERENCE?
Gabinete de Prevenção e Investigação de Acidentes com Aeronaves e de Acidentes Ferroviários. (2026). Impact with trees during go-around manoeuvre in brownout conditions: Leonardo Helicopters AW139, EC-JOU, Atei, Mondim de Basto, Portugal, 2 September 2024 (Report 2024/ACCID/05). GPIAAF.
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 