In 2023, the BEA published ten reports regarding accidents which occurred during helicopter operations.

The published reports only concern single-engine helicopters, four of which were destroyed and four others substantially damaged. The ten accidents occurred during the day, and in three of them the weather conditions were a contributing factor. Only one accident was caused by a mechanical failure, although this was not explained.

• Three occurrences highlight the fact that some private pilots did not take into account or even lacked knowledge of the characteristics and performance limitations of rotorcraft.
• Six reports address the risks that pilots may take given the manoeuvring possibilities of helicopters when flying in the vicinity of obstacles or terrain.
• One report deals with drug use.

In all these accidents, four people were fatally injured, two people were injured on board the helicopter and two others were injured by a sling or load.

France is a major state of manufacture in many aeronautical fields, particularly aircraft and engines. As such, the BEA takes part in many foreign investigations.

Every year, on average, the BEA is asked to appoint an accredited representative for more than 60 investigations conducted by foreign authorities into events involving helicopters. On average, some fifteen of these investigations concern fatal accidents.

1. Lack of knowledge of helicopter characteristics and performance

In 2023, as in previous years, three investigations showed a lack of knowledge or inadequate consideration given to phenomena specific to rotary wings (in particular unanticipated yawing). In addition, accidents occurred during instruction.

The accident to F-HOLA on 12 May 2022 at Aix-Les Milles highlights a safety issue already identified in the thematic reviews of previous years (2020, 2021 and 2022): loss of yaw control.

In this occurrence, the student pilot, alone on board, was about to turn left to vacate the runway when he lost control of the helicopter, which made two or three complete left turns around its yaw axis. The student pilot then lowered the collective pitch lever. The helicopter touched the ground and bounced before landing hard and flat on the runway. The student pilot could not remember which side of the rudder pedals he had actually pressed, or how much, and could not rule out having pressed the left rudder pedal.

The student pilot insufficiently took into account the direction of the wind on returning from a solo flight. He hover taxied over the runway with a right crosswind component whereas he had done this several times in dual control with a left crosswind component just before leaving for the solo flight.

The accident to F-HGRE on 18 February 2022 at Grenoble occurred in the same circumstances and in the same flight envelope. While hover taxiing to the parking position, with a right crosswind, the helicopter began to turn left on its yaw axis. The student pilot initially applied pressure to the right rudder pedal but not to full deflection, and was unable to counter the movement. The left yaw rotation was then amplified by the pilot pulling on the collective pitch lever to move away from the ground, followed by a left rudder pedal input, the pilot probably being disoriented by the high rate of yaw. After several turns, the helicopter collided with a pylon and fell vertically to the ground.

These two accidents show that awareness of yawing can be improved and that it may also be partly associated with the specific features of the Fenestron and its consequences in terms of manoeuvrability. They highlight the extent to which the instruction given and the mastery of helicopter piloting are demanding. They require actions that are prompt and consistent with the flight mechanics, such as taking into account that an input on the collective pitch lever automatically generates a reaction on the helicopter's yaw axis.

The vortex ring state (VRS) is a phenomenon familiar to helicopter pilots, but when it occurs close to the ground it is generally difficult, if not impossible, to recover from it. It is important for pilots to be constantly aware of the flight envelope in which they are operating. During the accident to F-HMFA on 30 May 2022 at Borce the experienced professional pilot carried out an approach with a high vertical descent speed with a tailwind. The helicopter used (an Airbus AS350 B3e) is reputed to have a substantial power margin when not operated at maximum weight. These intrinsic qualities of the helicopter can lead pilots to have excessive confidence in the helicopter's performance and in its ability to get out of tricky situations.

Airbus has published two information notices explaining the risks and the actions to be taken if exposed to the VRS: the conventional technique for exiting the vortex is described in SIN No 3123-S-00. This is supplemented by the Vuichard recovery technique described in SIN No 3463-S-00). Airbus has also developed interactive training.

These accidents did not give rise to corporal injury.

2. Control of the helicopter and its environment

Accidents during lifting operations

Helicopters are sometimes the only suitable means of bringing in and removing equipment in areas that are difficult to access. Operating sites are often complex, and pilots sometimes have to decide alone, on how to carry out the mission. They have to take into account the environmental risks, the weather conditions at the time, their own flying experience and latent commercial pressure. The accident to F-GJRP on 6 July 2022 at Phare de la Vieille lighthouse illustrates the constraints faced by crews. The momentary loss of control of the helicopter during external sling load operations resulted in the injury of a ground agent when he tried to hook on a load. Insufficient coordination between the operator and the customer in drawing up the prevention plan when the mission was being prepared, the absence of coordination between ground agents and the crew, the pilot not contacting the flight operations manager and insufficient consideration given to the weather conditions were contributing factors in the pilot's performance of the mission.

The complexity of certain operations linked to the manoeuvrability of helicopters can lead to situations that are difficult to foresee. During the accident to F-OMAB on 14 December 2022 at Ilet à Malheur, the pilot, accompanied by a flight assistant, had to set down a load in a rectangular walled pit using a 15 m long sling. After a quick reconnaissance of the site, the surroundings appearing to be secure, the pilot was hovering over the pit when the load pivoted slightly around its axis in the direction of a person who fell from the low wall without being hit by the load. The pilot, while setting down the load, was unable to detect this person, who was not taking part in the manoeuvres, as they were no longer in his field of vision.

Two people were seriously injured on the ground in the occurrences mentioned.

Occurrence as a result of landing on unsuitable ground

The accident to F-HOHE on 19 February 2022 near Etangs de Valojoulx also shows the helicopter’s manoeuvrability capabilities and the associated characteristics and even dangers that need to be taken into account (suction effect). In this occurrence the pilot indicated that he noticed variations in the engine speed when he was flying at low height over an aquaculture lake. He made an emergency landing on a dyke which he had reconnoitered during an instruction flight. The helicopter remained stable for about ten seconds, then the skids sank and the helicopter slid backwards. The pilot tried to take off again but the right skid of the helicopter remained stuck in the loose soil. Surprised, the pilot made an excessive input on the collective pitch control and lost control of the R44. The helicopter tilted to the right and forward, hit the surface of the water and then fell onto its right side.

The accident to F-HPTI on 3 April 2021 at Saint-Georges-de-Reneins also shows the inherent characteristics of flying a helicopter. Shortly after take-off, the helicopter jolted and yawed and a clacking noise was heard. The instructor, thinking that the failure was minor, turned around to fly back to the area used for the take-off. During this manoeuvre, the engine power decreased, possibly due to a sealing fault at the valves of one of the cylinders. The instructor then decided to make an immediate landing, with a tailwind of around 15 kt. During the running landing in a field with loose soil, punctuated with grooves and covered with a tarpaulin, the helicopter tipped forward and then onto its side.

The accident to F-HBKY on 19 July 2023 at Rivière-Saas-et-Gourby illustrates the continuous difficulty of controlling a complex aircraft. The pilot-in-command, the instructor, was accompanied by another pilot for an autorotation training session. He carried out a reconnaissance of the grass strip that was going to be used and the environment. The second pilot carried out a first autorotation, with the engine re-engaged on flaring and two complete autorotations (engine idling) up to landing. The pilot-in-command then took the controls and took off in order for him to carry out a complete autorotation. During the flare and on increasing the collective pitch, the helicopter still had a substantial forward speed and vertical speed. The helicopter made flat hard contact with the ground and slid on the grass. The main rotor blades struck the tail boom. All the conditions seemed to guarantee the safety of the exercise. However, manoeuvring the helicopter close to the ground means that the pilot must continuously accept that there is a risk. Certain factors, such as the quality and surface of the ground, also need to be taken into account during the landing, and require the pilot to continuously adapt the control parameters.

Two people were injured in the occurrences mentioned.

3. Collision with terrain in adverse weather conditions for a visual flight

The helicopter's manoeuvrability in flight should not exempt the pilot from complying with the regulations in force. A pilot can easily slow down his forward speed, or even stop and fly backwards, even near obstacles.

During the accident to F-HARY on 6 January 2022 at Pas de la Croix, the pilot undertook an outbound cross-country flight with an instructor having consulted the weather reports and forecasts several hours before take-off. They were already mentioning a cloud layer close to a planned passing point which the crew encountered and flew around for the outbound flight. For the return flight, the pilot did not consult the latest available weather information and followed another helicopter on which there was the instructor from the outbound flight. Confronted with clouds close to the terrain, the pilot flew at a low height. It is very likely that during a turn, the helicopter entered the cloud layer, depriving the pilot of external visual references and leading to spatial disorientation.

During the accident to 3A-MVT on 25 November 2022 at Villefranche-sur-Mer, the pilot, who was not qualified for instrument flight and had little training in blind navigation, reduced speed when faced with a meteorological hazard (sea haze), continued on his heading, entered the clouds and lost all external visual references. He then lost control of the helicopter which collided with the ground.

Although experienced in flight under day VFR, the pilot had not received sufficient training to fly without visual references and did not have clear instructions in the event of inadvertent entry into these conditions. Regular training based on realistic scenarios, as carried out by some operators, can provide backup tools: climb to a predefined safe altitude, maintain altitude, preconfigure power to reach a safety speed, perform a controlled U-turn and/or use radio navigation aids. This type of training does not release pilots from complying with visual flight rules and VMC conditions, but does ensure that they are better prepared for situations where they inadvertently lose external visual references.

Flight simulators are a good alternative for practising inadvertent entry into the cloud layer.

Four people were fatally injured in the occurrences mentioned.

4. Conducting a flight under the influence of drugs

The investigation concerning the accident to 3A-MVT on 25 November 2022 at Villefranche-sur-Mer revealed that the pilot had undertaken the flight while under the influence of cocaine and showed signs of recent consumption of CBD, THC and alcohol.

The pilot's profile was that of a surreptitious user in the habit of repeated transgressive use of cocaine in the months preceding the accident. The ability of these users to get around controls based on saliva screening tests, which at best detect drug consumption in the previous few days, explains why they remain unrecognised for so long. The deterioration in their abilities contrasts with their continuing high self-esteem, which prevents them from realising their true limitations.

In its report, the BEA sets out possible strategies to be considered for preventing the risks associated with the use of psychoactive products by crews.

Reminder of themes in previous years

Helicopter themes in 2022:

1. Lack of knowledge of helicopter characteristics and performance
2. Risks associated with flying near obstacles or terrain
3. Organizational weaknesses

Helicopter themes in 2021:

1. In-flight loss of control
2. Wake vortex generated by a helicopter
3. Near-collision with a drone

Helicopter themes in 2020:

1. Medical monitoring of crew
2. Loss of control