Aircraft Cabin Management

Long Read: The rules around restraints

photo_camera Schroth airbag belt

A technical and complex product, airline seatbelts are a crucial part of onboard safety. Alex Preston talks to two manufacturers about what’s making the safety restraint market click.

“Fasten your seatbelts; it’s going to be a bumpy night.” It’s a now famous line, spoken by Margo Channing, played by Bette Davis, in the 1950 movie All About Eve. But her warning is not referring to airline turbulence.
Aircraft seat belts would have been an all-too-familiar sight to cinema-going audiences at that time, after all, they had been introduced to passenger aircraft in the 1920s.
But while in the US seat belts had become mandatory in all types of aircraft by 1928, passengers were not required to wear them.
Controversy surrounding the dangers of seat belts dogged their use until the 1970s, despite studies showing the importance of seatbelts in aircraft accidents.
The danger of non-compliance was highlighted by the US National Transportation Safety Board report into the crash of Asiana Airlines flight 214 in 2013, at San Francisco airport.
The 777-200ER crashed on landing ejecting two passengers who were not wearing seatbelts. The subsequent investigation concluded that their ejection was attributed entirely to that fact and that they would otherwise have remained in the cabin and survived.
Safe from harm
As the Federal Aviation Administration (FAA) acknowledge, the purpose of those early seatbelts, was to prevent passengers from being tossed around or thrown out of the cockpit during turbulence or other manoeuvres.
During the 1940s, research shifted from restraints to crashworthiness – from restraining passengers to preventing injury and accidents.
Today, seat belts and safety restraints are manufactured and certified according to US Technical Standard Order (TSO) and European Technical Standard Order (ETSO) standards.
For seat belts and extensions these are TSO/ETSO C22g, and (TSO/ETSO C114 (Torso Restraint Systems), which are set against the minimal performance standards of SAE (Society of Automotive Engineers) AS8043 and AS0849.
There are only a handful of manufacturers responsible for producing the huge volumes of seat belts shipped each year. One is Schroth, which works as part of the SAE Seat committee to develop these standards.

While legislation has pretty much stayed constant for several years, there is a piece of forthcoming regulation whose effects will be felt widely by all stakeholders in passenger safety restraints.
This is coming in the form of the FAA Advisory Circular AC25.562-1b Change 2 “Dynamic Evaluation of Seat Restraint Systems and Occupant Protection on Transport Airplanes”.

As Schroth explains, this is a topic the SAE committee are tracking as it will have a big impact on front row seat restraint selections, requiring airlines to upgrade to either 3-point restraints, similar to automobiles, or lapbelt airbag solutions.
The Advisory Circular (AC) comment period for the proposed changes is closed, and everyone is awaiting a final release of the AC to understand the language and maximum period until mandatory implementation of restraint solutions on aircraft to address the AC.
Another seat belt specialist is Anjou Interiors, which over the last ten years has invested in new and modern machinery for its own testing laboratory to oversee crash tests, webbing elongation and abrasion testing, salt spray tests, FAR 25.853 flammability tests and much more.
As general manager, Alexandra Curca, says: “Seat belt production is a niche activity which requires a specific and rare know-how that we are proud to transfer from generation to generation.” The company has been doing this since 1948.
Anjou provides seat belts, adult and baby extensions for passenger seats (including the Y belts for the front row) as well as 3/4/5-points torso restraint systems with inertia reels for the attendant and cockpit seats.

Anjou belt

The firm is celebrating 25 years since it certified its seat belt type 349 and 10 years since launching its rotary buckle type 358 originally destined for Airbus Helicopters but currently flying in various types of helicopters and planes.
Curca says the company closely collaborates with its customers who contribute to development programs through their constant feedback.
“This is how our new, more ergonomic and lighter rotary buckle type 368 came to life,” she reveals. The product was showcased at this year’s Aircraft Interiors Expo in Hamburg.

Three-point turns

Seat belt performance is dependent on proper use and fit. Ten years ago, Curca says, the trend was to lighten the products and as a response to this request Anjou developed and certified its light buckle type 353.
Nowadays, she says, the major change is related to Business and First-Class seats on which the standard seat belts (with or without airbag) are replaced with 3-points torso restraint systems with inertia reel on the shoulder strap.
Anjou has successfully installed this product in Airbus helicopters, Daher Socata, Cessna planes, and others, for more than 20 years.
“The recent market evolution [has] had a positive impact on our sales,” reveals Curca. “Thirty percent more 3-points torso restraint systems delivered in 2022 compared to 2021.”
For Schroth, Business Class presents a different issue. As the company identifies, herringbone seat configurations with large oblique angles are becoming a popular design trend to maximise occupants in this cabin space.
The technical challenge, says the company, is during a forward dynamic crash event, where there are high side loads on the passenger neck and hard surfaces to the side of the head that can lead to head impact. This requires more complex restraint solutions than a standard lapbelt or 3-point restraint.
Another challenge is posed by Premium Economy, where new seat designs with external hardshells are emerging.
The technical challenge here, according to Schroth, is standard seats fold forward during a crash event, providing additional distance between the passenger head and impacting the seat.

Schroth airbag belt

With a rigid shell, that impact distance is reduced as the shell doesn’t move during impact. With airlines wanting to maximise the number of rows in the Economy/Premium Economy sections, this makes it difficult to find solutions to the reduced distance, requiring more expensive solutions such as lapbelt airbags.
Intelligent seat belts
In 2018, at that year’s AIX in Hamburg, ACM Aircraft Cabin Modification launched its proprietary seat belt, “Smart Belt”.
Using sensor technology connected to an app, crew can check whether passengers have fastened their belts, at any time and interference-free.
If a passenger is injured during turbulence, it can be proven whether the seat belt was fastened or not. In the case of possible compensation claims, this fact can prove to be a significant advantage.
According to ACM, the integrated technology does not add additional weight to the belt.
Commenting at the time, Roger Hohl, managing director of ACM said: “We are certain that this product will make a significant contribution and provide added value to worldwide safety in aviation.

ACM Smart Belt

“In turn, this will have a direct influence on the reduction of incidents and injured persons due to passengers with incorrectly fastened seat belts — at all stages of a flight.”
Schroth says it has begun to receive inquiries into “connected cabin” concepts. Monitored buckles for seat belts have been developed for more advanced restraint concepts like lapbelt airbags, but these require their own power source in the form of an underseat battery unit.
As the company warns, unless every seat integrates into the aircraft power system, which can drive up costs, a monitored buckle solution will not be feasible. “We expect more demand for monitored seat restraints in the eVTOL (electric vertical take-off and landing) market, especially for autonomous piloted passenger carrying vehicles,” the company says.While its customers have yet to show a real interest in seat belts with sensors, Anjour says what is noticeable is its customers’ interest in customised seat belts and tailor-made solutions.
“We propose a large variety of webbing colours (even though blue and grey shades continue to be the favourite choice for many airlines) and have also invested in laser engraving machines,” says Curca.

“While the technical characteristics stay the same, the seat belt, as a part of the cabin interiors, can of course be customised to match the airline’s colours and global brand image,” she adds.
“The seat belt must be safe and stylish while, technically, standardised but still customisable and this is the real challenge and what makes our work so interesting.”

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