Avoiding Collisions with Rotor Blades

Michel MASSON • 20 February 2024

in community Rotorcraft

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Avoiding collisions with rotor blades is easy, don’t walk into them! Well, that isn’t always easy in practice unless proper risk controls are in place.

Helicopters are working machines that do amazing things for our communities in challenging conditions. But helicopter operations involve hazards that must be controlled to ensure safe operations.

This is where the hierarchy of risk controls are a great place to start because it organises the types of interventions that various actors (for instance OEMS, organisations, pilots, passengers) can take to eliminate, control or protect from the hazard of colliding with rotor blades.

Key Advice for OEMs:

Use engineering protections (like a Fenestron).
Increase hazard awareness by using visible colours, markings and signs.
Provide guidance to enhance passenger safety briefings and management of people approaching the helicopter.
Provide pilots with training on spatial awareness and obstacle avoidance.

Key Advice for Pilots:

Continually train on spatial awareness and obstacle avoidance.
Maintain vigilance when manoeuvring close to obstacles.
Brief passengers and people on the ground to increase hzard awareness and avoid being hit by rotor blades.

Key Advice for Passengers:

Follow pilot and crew instructions carefully.
Be aware of rotor blades at all times.
Use designated paths for embarking and disembarking.

More detailed information is provided below, using safety material published by Airbus Helicopters, Robinson Helicopter, IASA and EHEST, and the Vuichard Recovery Aviation Safety Foundation (VRASF). It starts by introducing the hierarchy of risk control classically used by the European Union Information Agency for Occupational Safety and Health (EU-OSHA) and its US counterpart the National Institute for Occupational Safety and Health (NIOSH). It transfers across well to aviation safety.

Hierarchy of risk controls

The concept of Hierarchy of Risk (or Hazard) Controls is a multi-layer system of prioritised interventions to eliminate, minimise or mitigate exposure to hazards.

Depending on the source, the hierarchy of risk controls may feature 5 to 8 levels of control measures. Here is an example of a classical 5-level hierarchy:

Elimination - Eliminating a hazard or risk completely is the strongest control possible because no hazard means no harm. This is rarely possible in aviation because aviation involves operations where hazards and risks are unavoidable.
Substitution - Substitution is the second-best option. It consists of replacing a hazard or risk by a lesser one. Again, this is not always possible.
Engineering controls - Engineering controls involve making changes to the hazard or situation to isolate people from the hazards, increase awareness, reduce exposure or consequences. Controls include air conditioning and climate control, filtering, noise reduction, lighting, high visibility paint and use of reflective material, markings, placards, posters and technical equipment such as Crash Resistant Fuel systems (CRFS),Crash Resistant Seats and Structures (CRSS), engine cowlings, Fenestron, etc.
Administrative controls - Administrative controls include regulations, rules, guidance material and guidelines, Standard Operating Procedures, good practices, training, safety promotion and communication.
Personal protective equipment (PPE) - PPE is the best known but also weakest in the hierarchy of controls because it is aimed at limiting hazard effects. PPE includes clothing (e.g. pilot, hoist operator, mechanic and firefighter suits), gloves, legging, arms and body protections, safety glasses and face shields, helmets and hard hats, safety shoes, ear plugs, safety masks and respirators. (Article - 10 Types of Essential PPE)

A safety strategy usually combines different types and levels of control measures and should not be limited to PPE.

The strategies presented in this article combine hazard elimination and isolation, engineering and administrative controls to help think in a more structured way about how to avoid collisions with rotor blades.

The first example considers the importance of increasing tail rotor blade conspicuity by using a high visibility paint scheme. The second one addresses decreasing the potential of passengers being struck by rotor blades. And the last one provides tips to pilots to avoid main rotor blade collisions with ground obstacles.

1. Airbus Helicopters SIN No. 3982-S-64 Tail Rotor

Product Enhancement – High visibility Tail Rotor Blade.

On January 31, 2024Airbus Helicopters published SIN No. 3982-S-64 Tail Rotor. It is available on AirbusWorld | Airbus, the password-protected collaborative customer platform.

Airbus Helicopters is regularly aware of fatal accidents to third parties caused by the spinning tail rotor blades on the ground, including a recent case during a ground loading operation with the rotors turning.

Following these events and to continuously improve product operational safety, Airbus Helicopters has implemented a modification of the AS350 B3 / C3 tail rotor blade definition by introducing a high visibility paint scheme, which led to the creation of a new advice to operators. This modification aims to increase the visibility of the spinning tail rotor to enhance passenger and ground personnel safety during operations.

2. Robinson Safety Notice 44 Carrying Passengers

Safety Notice 44 Carrying Passengers is freely available on the different channels from Robinson Helicopters, including Robinson Safety Notices - Robinson Helicopter Company.

It is accompanied by a video presented by Monica Campos, Robinson Helicopter Company, Flight Safety Department:

Robinson Helicopter Safety Notice 44: Carrying Passengers (youtube.com)

The key messages are:

Carrying passengers in an additional responsibility for the pilot in command. Passengers should be advised of the risks associated with every flight. Carrying a passenger increases risk because it adds workload and distractions.
Always conduct a safety briefing before allowing a passenger on board. The briefing should include safe emergency entry and exit path, away from tail rotor and within the pilot’s view. Do not board or disembark passengers with rotors turning unless procedures, such as ground escorts, are established before the flight.

3. IASA and EHEST Passenger Management videos

Two complementary videos published in DSAC’s Collections on Vimeo are aimed at pilots and passengers.

Version for Pilots

This video provides advice to pilots to ensure passenger safety on the ground and in the air:

IASA EHEST Helicopter Passenger Management - Version for pilots on Vimeo

Messages include:

If you arranged to pick up your passengers away from an airfield, give them clear instructions before your arrival.
Ensure that the landing area is clear of any loose article that can be blown by the rotor downwash into the rotor disk.
Emphasise to passengers that no one should approach the helicopter until the rotors have stopped and only when instructed to do so by the pilot.
Increased vigilance is required when children and pets are in the vicinity.
Escort the passengers to the helicopter and help them board one by one, showing them where they can place their feet and hands.
If boarding operations must be carried out with the rotors turning, these operations should be subject to strict procedures and should be normally conducted with ground assistance. Embarking and disembarking the helicopter require the same safety precautions.
Even if your passengers are familiar with the helicopter, remind them of the dangers of the rotor blades. Special attention should be paid to the main rotor blades, especially if passengers are tall or if the helicopter is on a slope. The tail rotor must not be ignored!

Version for Passengers

The second video provides advice to passengers to ensure their own safety on the ground and in the air:

IASA EHEST Helicopter Passenger Management – Version for Passengers on Vimeo

Messages include:

If a helicopter must pick you up away from an airfield, ensure that there is a large area kept clear around the landing site until the helicopter has landed and the rotors have stopped turning.-If the helicopter is landing in your (or someone else’s) property, ensure that the landing area is clear of loose articles that could be blown by the rotor downwash into the rotor disk.
Children and pets should be monitored at all times!
Only approach the helicopter when instructed to do so by the pilot.
Even if you are familiar with the helicopter, it is safer if you are escorted by the pilot or qualified personnel.

3. Avoiding a main rotor collision with obstacles

Claude Vuichard has released this VRSF video in the VAST ESPN-R Safety Workshop - Unanticipated Yaw (europeanrotors.eu) of 2023 in Madrid:

How to avoid a main rotor collision with obstacles (youtube.com)

Messages include:

Collision of the main rotor with obstacles often occurs because pilots misjudge the effective rotor radius. The perception of the main rotor radius from the pilot’s seat or co-pilot’s seat doesn’t correspond to reality since the crew station is not under the rotor mast: the rotor radius perceived in the front is shorter than the actual distance.
The difference between the perceived and the actual distance depends on the helicopter type and thus on the distance between the crew station to the rotor mast. Depending on the type of helicopter, the distance can be more than twice that of the perceived distance between the pilot’s eyes and the tip of the rotor blade.
The greater the distance between the rotor mast and the pilot’s eye point and the smaller the rotor radius, the greater the risk of the main rotor colliding with a lateral obstacle, especially on the side opposite to the pilot.
Never land or taxi sidewards closed to a fuel station without clear markings for helicopters from the airport authority. Markings should indicate the maximum rotor diameter allowed.
Whenever possible, approach the obstacle with the nose of the helicopter and not sideways, and land the helicopter in the fall line and never on the side of the slope.
Have whenever possible a qualified marshaller with radio contact for guidance for all operations close to obstacles.