HESLO Dynamic Rollover in Alaska

HESLO Dynamic Rollover in Alaska (Trans Aero AS350B3 N354LA)

On 25 July 2018 Trans Aero Airbus Helicopters AS350B3 N354LA was damaged in a Helicopter External Sling Load (HESLO) accident 23 miles from Kobuk, Alaska.

Airbus AS350B3 N354LA After Dynamic Rollover Doing HESLO in Alaska (Credit: Trans Aero via NTSB)

Airbus AS350B3 N354LA After Dynamic Rollover Doing HESLO in Alaska (Credit: Trans Aero via NTSB)

The US National Transportation Safety Board (NTSB) explain in their safety investigation report (published 27 May 2021) that the pilot had 5061 hours of flying experience, 225 on type and was transporting equipment in support of remote mining operation using a 100-foot long-line.

During takeoff, and while preparing to lift the external sling load, he inadvertently allowed the helicopter to drift laterally to the right and the right skid struck the ground, resulting in a dynamic rollover. The helicopter continued to roll to the right, and the main rotor blades struck the ground.

Airbus AS350B3 N354LA After Dynamic Rollover Doing HESLO in Alaska (Credit: Trans Aero via NTSB)

Airbus AS350B3 N354LA After Dynamic Rollover Doing HESLO in Alaska (Credit: Trans Aero via NTSB)

The helicopter subsequently came to rest on its right side, sustaining substantial damage to the main rotor drive system, fuselage, and tail boom. The pilot sustained minor injuries…

There were no pre-accident failures or malfunctions with the helicopter that would have precluded normal operation.

The NTSB determined the Probable Cause to be:  The pilot’s inadvertent dynamic rollover during takeoff.

Airbus AS350B3 N354LA After Dynamic Rollover Doing HESLO in Alaska (Credit: Trans Aero via NTSB)

Airbus AS350B3 N354LA After Dynamic Rollover Doing HESLO in Alaska (Credit: Trans Aero via NTSB)

Safety Resources

The European Safety Promotion Network Rotorcraft (ESPN-R) has a helicopter safety discussion group on LinkedIn.  You may also find these Aerossurance articles of interest:


Aerossurance‘s Andy Evans will be running two training sessions at European Rotors in November 2021.  One will be on safety leadership and the other on how to procure and assure aviation services.  He discussed these in a recent European Rotors Digital Series interview:

european rotors interview


Aerossurance has extensive air safety, operations, SAR, HESLO, HEMS, airworthiness, human factors, aviation regulation and safety analysis experience.  For practical aviation advice you can trust, contact us at: enquiries@aerossurance.com