Hélicopters - 2021
In 2021, the BEA published 10 reports concerning occurrences during the operation of helicopters. These reports concern accidents that resulted in the fatal injury of three people. Two other people were seriously injured and three suffered more minor injuries.
These events, which all occurred during the day, mainly involved light single-engine helicopters. Only one accident involved a twin-engine helicopter.
1. In-flight loss of control
In-flight loss of control was already one of the topics of the 2020 safety lessons (five reports were then published concerning accidents during which two people were fatally injured and two people were injured).
In 2021, five reports published by the BEA relate to this issue. These reports concern accidents that resulted in the fatal injury of two people. Two other people were seriously injured and three suffered more minor injuries.
These accidents bring to light the insufficient consideration given to specific phenomena associated with flying a helicopter, in particular at low height, which require the pilot to act quickly. In most of these cases, the loss of control initially resulted in a yaw that the pilot was unable to control. For example, this was the case with the accident to F-GBOO on 26 April 2020 at Sète. The pilot took off from a prepared helipad. The helicopter was then close to the maximum take-off weight. During a straight-line flight, the pilot lost control and the helicopter rotated several times about the yaw axis before crashing into a field. The investigation revealed that the helicopter was flying with a right-hand tailwind of about 10 knots and in light to moderate turbulence. These conditions, combined with the slow forward speed of the helicopter, were conducive to an unanticipated yaw (commonly referred to as loss of tail rotor effectiveness (LTE)).
Similar occurrences published in 2021:
The accident to F-GILS on 7 September 2017 at Mulhouse-Habsheim was also the result of a loss of control, this time, during an instruction flight, due to the student-pilot’s rough input on the cyclic pitch stick during an exercise close to the ground. This was the student-pilot’s first flight. This flight, which was scheduled to last 30 minutes, did not allow the instructor to fully check the student-pilot’s dexterity and responsiveness in performing an exercise of this kind. Due to his lack of anticipation, the instructor was unable to regain control of the helicopter before it struck the ground.
The last published report that falls within the category of loss of control in flight concerns the accident to F-HGJL on 2 May 2018 in Guyana. This accident occurred in adverse weather conditions for VFR flight, the pilot having no instrument rating and no night rating. This accident also comes under the topics “Services for third parties” and “Pressure caused by the carrying of passengers and the ‘group effect’” addressed in the Light aeroplanes section.
This report contained a safety recommendation addressed to the DGAC concerning own-account air transport.
2. Other noteworthy topics
While these are not topics which have been brought to light by recurring events until now, the BEA would like to point out two additional reports published in 2021, one concerning wake vortex generated by a helicopter, the other concerning the risk of mid-air collision with a drone.
Wake vortex generated by a helicopter
The topic is addressed in the report on the accident to F-HTIN on 11 May 2019 at Le Conquet. On arriving at the site of an emergency intervention, the pilot identified a paraglider on his right. When the paraglider crossed the wake vortex generated by the helicopter, this led to the wing closing. The helicopter pilot’s rapid approach to the landing area at low height left himself, and the paraglider, with limited room for manoeuvre. The low-height manoeuvres of the paraglider did not enable him to regain control of the situation before colliding with the ground.
This accident showed the aeronautical community’s (operators, pilots and certification authorities) lack of knowledge with respect to the wake vortex generated by a helicopter and the associated risks when flying in confined areas or when no site reconnaissance has been carried out.
To share the risk associated with helicopter wake vortices with the aeronautical community, the BEA produced a video, which is available on the Internet. The report contains one safety recommendation addressed to EASA.
Near-collision with a drone
The topic is addressed in the report on the serious incident to F-OIAS on 15 December 2020 in New Caledonia. The pilot took off for an aerial photography mission in a restricted area. At the same time, another operator was performing an aerial photography mission with a drone in the same area. The helicopter pilot detected the presence of the drone slightly above his path, requiring him to perform an evasive manoeuvre.
The two operators had received clearance from the manager of the restricted area to enter the area. However, the manager of the restricted area did not notify the operator of the drone and the operator of the helicopter of their concurrent presence in the same area.
The development of the drone industry introduces new risks, including mid-air collisions with manned aircraft. More specifically, this serious incident may help actors realise that drones and helicopters have common missions in their field of operation. These two types of aircraft may therefore find themselves in the same areas of interest at the same time, more often than not at low height, which increases the risk of mid-air collision.
Other reports published in 2021
Reports on the following accidents were also published in 2021. These accidents only resulted in damage to equipment.
- Accident to F-HLXO on 30 October 2020 at Thiézac: interference of the sling with the tail boom and the tail rotor, emergency landing
- Accident to 3A-MLC on 26 September 2019 at Col de Véry: engine in-flight shut-down, autorotation, damage to the drive shaft by the main rotor when landing in a field
- Accident to F-GHOO on 6 June 2021 at Marennes: tail rotor strike with the runway during an autorotation exercise, in instruction