Special missions are not homogeneous. Each sector, each role and each circumstance has special and distinct requirements and demands on the personnel that serve to achieve a safe and successful mission. The equipment used for these missions has to be fit for purpose, designed with the experience and knowledge of the needs expected from the situations that they go into. One of the most vital and essential items of protective equipment is headgear.

Safety

Helmets serve the primary purpose of protecting the user’s head in the event of an impact, such as one caused by a bird strike or a hard landing. But not all impacts are the same, and not all impacts are expected with the same force. Aviation, and special missions particularly, are prone to more frequent and possibly stronger head injuries than, for instance, a casual cyclist might experience, and so the safety and security that the helmet provides must be considerably more substantial than a thin plastic shell and some soft polystyrene foam. Formerly made from leather, modern flight and crew helmets are made from a variety of materials to provide the greatest resistance to damage for the lightest weight and lowest profile.

JJ Smith, Pilot for the Great North Air Ambulance Service (GNAAS), detailed the most common risks for head injury that he and the crew have to be aware of: “Mainly birds, and foreign object damage for the crew when they disembark or are outside for the engine start.” This is because special missions aircraft often have to land or hover close to an incident that could be on a mountain, or a field, where small, sharp flying objects can be a serious danger. These loose articles from the ground are not always avoidable, especially when special missions take one to locations and environments that are not designed for aircraft landing or proximity, so helmets need to be capable of resisting these injuries from loose articles disturbed by wash, or by birds surprised by the aircraft.

When choosing helmets, safety is always at the front of a user’s mind, whether that is the individual wearer or the organization the wearer works for. John Fyall, EAMEA Communications and Marketing Manager for Bristow Group, explained: “Bristow selects equipment based on a variety of criteria, but primarily on safety and functionality. We work closely with our operational teams and manufacturers to ensure we provide our people with the right equipment for the tasks they deliver.”

Generally, the shells of flight helmets are composed of a complex blending of carbon and aramid fibers mixed with polyethylene and epoxy resin. Forming the shell this way allows for better molding before it has been set, and then a thin, rigid, lightweight and robust casing once it has hardened. A shell alone is not sufficient to prevent damage from impact shocks and partial penetration, so an inner cap is made from high-density expanded polystyrene foam, plus a polyurethane foam cushion. A liner is also installed to embrace the head without either gripping it too hard or allowing space for it to rattle about.

A heavy and bulky head covering will be physically obstructive and the strain on the head, neck and shoulders will be unbearable, causing fatigue and reducing effectiveness

In the most extreme situations, militaries and some police forces require ballistic protection and helmets (or helmet covers) are made with denser aramid fibers to greater resist penetration by projectiles.

A light weight and a low profile are important for flight operations because, if you are required to spend long hours every day in a restricted and cramped environment, a heavy and bulky head covering will be physically obstructive and the strain on the head, neck and shoulders will be unbearable, causing fatigue and reducing effectiveness. Furthermore, the base helmet is never used alone, and numerous attachments and additions to aid in the job all contribute to the weight and profile of the headgear.

Attachments

Although many crewmembers often have the same base helmet, the expense of having a fully personalized and fitted item is often out of reach for many operators, especially those that are charity-funded public sector organizations. As people perform different roles on the crew of a special missions operation, the helmets deviate from one another either in their entirety or from the attachments and modifications to the base model. For instance, the expense of an added night vision goggles (NVG) mount is redundant if night operations are not required. Describing the attachment needs for the operations of the Norwegian Air Ambulance, Håvard Mattingsdal, HEMS Technical Crew Member (HCM) and Instructor, said: “The pilot and HCM can attach NVG during night operations. The medical crewmember (MCM) can attach a face shield during confined area landings or short-haul rescue missions. Crewmembers can also optionally attach a ‘lip-light’. During rescue missions the HCM can attach a Lupine headlamp to the Team Wendy helmet.”

A rescue swimmer needs a helmet that isn’t going to get waterlogged, and will need to be able to fit goggles and a breathing apparatus

Additionally, medical crews may need easy access to their ears for easier communication with a patient or to use hearing devices for diagnoses, and so a full helmet that covers the ear may not be acceptable. A rescue swimmer, similarly, needs a helmet that isn’t going to get waterlogged, and will need to be able to fit goggles and a breathing apparatus. Maritime or coastal rescue crews would also look to add saltwater protection for their equipment, much more than an inland ambulance crew would, for instance. Additional water functionality is needed for rescue swimmers; Mattingsdal described the added requirements and benefits of waterproof technology: “In our operation, the HCM operates as a rescue swimmer. This demands a helmet that has communication which easily can transfer from use in the cockpit to outside use, e.g. mountain- or water-rescue operations. The Team Wendy helmet is certified for both land and swiftwater operations, and the Sordin headset is also water resistant and can be used with a portable intercom radio (MP50 from Axnes), which allows the HCM to have the same situational awareness as the rest of the crew.”

Noise reduction

Aircraft are noisy. Wind and weather are noisy. Extreme situations that require medical aid and rescue are noisy. If it is to be expected that anyone should or could have a long career in special operations, then hearing protection is just as important as saving the head from physical trauma. The construction of a helmet from the hard shell and inner foams does go some way to reducing the amount of noise that can reach the ears, but it is primarily the ear cups themselves (which are often a part of the integrated headset) that really dampen the unwanted sound from damaging the ears. Positioning of the cups is vital for them to sit comfortably and surround the ear to give a snug and secure fit to prevent bleeding of sound into the ear canal. As well as having a tight fit to keep sound out, it must also be comfortable, so as not to cause pressure sores or irritation. The materials for the cups are often also a light memory foam composite to provide both muffling and a soft contact. Sometimes these are supplemented with communications ear plugs, depending on the roles and use, to further protect the ear canal but also allow the needed communications to come through.

Within the cups is often a standard ear piece or, as is becoming more common, active noise reduction (ANR) earphones

Within the cups is often a standard ear piece or, as is becoming more common, active noise reduction (ANR) earphones. Aware of the benefits of ANR, Christine Koch, Executive Sales Director for Commercial Helicopter Services, said: “Lightspeed Aviation is a leader in the aviation market for this technology. Paraclete’s Aspida helmet offers their version of Lightspeed’s H-Mod product. This product alleviates the ear pressure derived from noise with ANR. Many users find this solution to be more comfortable and worth the investment.”

Also speaking of the options for pilots and crew due to noise hazards, Mattingsdal said: “ANR is optional for all crewmembers with the Gentex ALPHA helmet. All crewmembers also have the opportunity to get customized ear plugs. Most HCMs and MCMs use double ear protection (both ear plugs and the integrated headset) due to frequent work outside of the aircraft while the rotor is running.”

Weight and distribution

The amount that the helmet weighs is not the only consideration regarding weight. Careful consideration of the distribution of the mass around the head is also important. It’s no good having a light helmet if it keeps sliding forward over your eyes because all

Using poorly fitted NVG can tip the head in the wrong manner, consequently adding an extra challenge to maintain head control to the already fatiguing experience of operating in low- or no-light conditions

the mass is collected towards the front. Having the right balance also helps to prevent strain on the neck muscles that would otherwise be working harder to keep the head upright. Weight distribution isn’t just limited to the helmet itself, but the attachments can throw the balance off as well. Using poorly fitted NVG can tip the head in the wrong manner, consequently adding an extra challenge to maintain head control to the already fatiguing experience of operating in low- or no-light conditions. Smith explained that, although the helmet he wears is 1.7kg, GNAAS do not fly long missions and so fatigue is not as considerable as it might be if they did: “[Our helmets] seem well balanced and have little impact on fatigue as we operate short hops – our longest tend to be around 20 minutes.”

To adjust for changes in weight distribution due to added equipment, there are solutions that enhance a secure and balanced fit, Koch explained: “Paraclete incorporates a dial retention system that comfortably secures the helmet to the head. This becomes important during NVG use or with more attachments.” Neck supports and other supplemental items are further used to support the head and reduce fatigue.

Buoyancy and other considerations

Although most helmets are a simple dome, the aerodynamic properties are not an influence on the design. That being said, the hydrodynamics are important if you are expected to be submerged at any point. Rescue swimmer helmets have to maintain buoyancy, allow water to flow through vents to ensure they don’t fill up, and need to be able to be compatible with goggles and breathing apparatuses. Rescue swimmer and mountain rescue helmets may also have grilles over the vents to prevent debris or dangerous loose articles from accessing the helmet.

Lifespan

Although there is a cost involved with purchasing a new helmet, barring major incident, some are capable of lasting decades over a career. Smith has had his for over 15 years: “I have had mine since 2008 and it’s still going strong.” He explained that good care and regular servicing helps his helmet’s longevity: “A yearly service keeps on top of everything and it’s stored in a padded helmet bag.” For the servicing, Smith added: “[GNAAS] use a company called Key Survival Equipment.”

The recommendation from many manufacturers is that a helmet’s lifespan is typically at least 10 years

The recommendation from many manufacturers is that a “helmet’s lifespan is typically at least 10 years,” said Koch. She added that regular inspection and refurbishment keeps a helmet in a good and safe condition: “The industry recommends that the helmets are visually inspected pre-/post-flights. The helmet maintenance plan should include a minimum of annual inspections and three-year refurbishments.”

Regulation/standardization

The US Department of the Interior and US Forest Service issued the Aviation Helmet Standard, last updated in November 2019. The standard was introduced to provide American civil aviation with guidance on helmet design and construction, including safe parameters for “crown and side impact, sound attenuation, retention, and weight”. That being said, there was some controversy around the standard when it was first published. And, as operations are conducted around the world, there are calls for standards, regulations and more robust safety measures outside of the USA. The benefits of helmets for special operations flights cannot be denied and any avoidable injury or fatality should prompt authorities and regulators to greater action to permit greater availability and accessibility of this vital equipment.