Several types of seat belts and restraints are installed on every airliner. Find out how they work and why they are so important. Buckle UP! Pilot, Cabin Crew & Passenger Seat Belts.
Passenger Seat Belts
Passenger seats and seat belts are designed to withstand loads that can be expected in a survivable accident. Aircraft manufactured prior to 2009 were required to have seats and belts that could withstand a 9g static load.
Newer planes must have seats and seat belts that are certified to withstand loads up to 16g using updated testing methods that more accurately simulate a real accident.
Why no shoulder belt?
Every car has a shoulder belt, but we rarely see them on airliner passenger seats.
Shoulder belts present a few problems on airliners. Seats would need to be stronger and heavier to accommodate the belt. The upgrade would be expensive and ultimately raise ticket prices for a statistically small increase in safety.
Convincing every passenger to use shoulder belts (and use them correctly) would be difficult. Flight attendants have a hard enough time getting passengers to wear a simple lap belt.
Without a shoulder belt, won’t a passenger’s head hit the seat in front of them in an accident? Believe it or not, that’s part of the plan…
Head Injury Criterion
The Head Injury Criterion (HIC) is a formula that was developed in the 1960s to quantify head injury risk for the automobile industry. HIC is now used in many industries, including sports equipment, playground design, and airplanes.
HIC uses the time and acceleration rate of a human head prior to impacting an object (like a seat back) to generate an injury risk value.
A 1988 FAA regulation requires that airline passenger seats have an accident HIC value under 1000. HIC values above 1000 are considered life threatening.
Here’s the formula for mathematically inclined readers:
Economy/coach seating rows are close together – we complain about that, right? It’s actually a safety feature. Airline seat backs are designed to absorb the energy of an impact.
During a crash, the short distance between rows keeps a passenger’s head from accelerating enough to generate HIC values above 1000.
Rows that are spaced farther apart will generate higher HIC values. The passenger’s head has more time to accelerate before seat back impact.
The famous “brace position” found on every airline briefing card is really important. Resting your head against the seat in front of you reduces your HIC value, which reduces the chance of serious head injury.
No School Bus Seat Belts
Most public school buses in the U.S. operate without seat belts. Similar to airline economy seats, bus seats have closely spaced rows and seat backs designed to absorb an impact. This keeps HIC values low for small children. Pack the passengers in tight and they won’t move as much in a sudden stop.
The Old-Fashioned Buckle
The “lift-cover” seat belt buckle has been used on airliners for decades. Cabin crewmembers demonstrate its use before every flight because, believe it or not, some passengers aren’t familiar with it.
Resembling an automotive buckle from the late 1950’s, the lift-cover buckle has benefits that make it well suited for airline duty:
- Simple design & operation
- Resists unlatching during impact
- Easy for rescuers to release in an evacuation.
- Self-Clearing Mechanism: The lift-release buckle has an opening on the bottom. Debris inside the buckle from dirt, peanuts, and Oreo cookie crumbs is ejected when the connector is inserted into the buckle.
The next time you fly, be sure to practice buckling and unbuckling your seat belt a few times so you can do it quickly in an emergency.
The AmSafe Seatbelt Airbag
The FAA’s Head Injury Criterion rule presents some challenges for certain types of aircraft seats.
Some first class and business class seats have too much space between the rows and can’t be certified without an alternative way to meet the 1000 HIC requirement.
Seat belt manufacturer AmSafe came up with an innovative, FAA approved solution. An airbag integrated into a passenger lap belt.
According to AmSafe, the Seatbelt Airbag meets the 16g Head Injury Criterion (HIC) requirement for commercial passenger seats and is a complete solution for the updated seat belt requirements in FAR/CS/25.562.
On a recent Singapore Airlines flight, my business class seat was equipped with an AmSafe Seatbelt Airbag. The seat belt is a little heavy; it’s quite a bit thicker than a normal belt. The Seatbelt Airbag is padded and quite comfortable. After wearing it for a few minutes, I forgot it was there.
The AmSafe website states: “Over 150,000 AmSafe Airbag Systems are in-service on over 100 airlines.” Keep your eyes open next time you fly. Chances are pretty good you’ll spot one.
The Golden Age of Aviation wasn’t that golden.
Airlines in the 1930’s didn’t bother with passenger seat belts (pilots had them). When airplanes crashed (as they often did), passengers enjoyed their last moments sailing through the cabin. 😯
At least they had comfy wicker chairs!
The Occasional Shoulder Belt
Instead of using the AmSafe Seatbelt Airbag, an alternative solution to first/business class seat certification is an automobile-style shoulder belt. A few airlines have chosen this option to satisfy the HIC regulation requirements. Again, the problem with a shoulder belt is that it must be worn properly to gain any safety benefit. The extra complication of the belt often causes passengers to take it off. If you are sitting in a business class seat with a shoulder harness, take care to wear it properly for takeoff and landing. It won’t help you if you don’t wear it!
Seat Belts Have an Approval Label
Airlines can’t buy seat belts from the local auto parts store. All aircraft restraints must be manufactured to standards agreed upon by international safety agencies. The document most widely used to specify passenger seat belt standards is FAA Technical Standard Order TSO-C22g (warning: boring government document).
Every airliner seat belt should have a label with an FAA, CAA (UK), or EASA (Europe) approval code attached. The labels are made of fabric or metal and indicate that the seat belt has been approved for use on an aircraft. The label will list:
- Name and address of the manufacturer
- Model name or part number of the seat belt
- Serial number or date of manufacture
- State Safety Agency Approval/Authorization code
Common approval/authorization codes found on labels:
- FAA TSO (or European ETSO) code: TSO-C22g
- CAA (UK Civil Aviation Authority) code: CAA AR663
- EASA (European Aviation Safety Agency) approval: EASA.21O.10029419
Before you buckle your seat belt, flip the strap over and look for the label. The label with a TSO (or similar) code means it’s a real, certified piece of fancy airliner equipment. Label designs and information will vary depending on the country of registry.
Note: Some tags are hidden by cushions, trim, and padding, especially in first or business class seats. Don’t be too concerned if you can’t find the tag. The airline checks them during scheduled maintenance.
What happens if the label is missing?
Airline maintenance technicians check the seat belts during scheduled maintenance. Seat belts that are damaged or have missing labels are removed and returned to the manufacturer for overhaul or replacement.
3000 Pound Passengers?
Many labels indicate the belts are rated for 3000 lbs (1360 kg). The airlines don’t expect to carry 3000 pound passengers!
Passenger seats and seat belts are certified to withstand 16 G’s of force during an accident. The required strength of a seat belt can be calculated by taking the average passenger weight of 170 pounds and multiplying by 16 G’s.
170 lbs x 16 G’s = 2710 lbs
Manufacturers round up to a nice and neat 3000 pound rated seat belt.
Flight Attendant Seat Belts
Regulations require that flight attendant seats have over-shoulder straps to protect the upper torso. A single point, quick release buckle is also required.
Unbuckling the four-point harness is easy. When the buckle is rotated, all straps are released. There are several seat belt manufacturers, so buckle design can vary at different airlines and on different aircraft.
The four-point harness is designed so flight attendants can quickly get out of their seats. This helps them accomplish their primary job of helping passengers evacuate the aircraft in an emergency.
Broken Flight Attendant Seat Belt?
If a cabin crew seat belt harness (or seat) is broken, the seat can not be used.
The flight attendant will be assigned a passenger seat as close to the exit as possible. If the flight is completely full, a passenger will be denied boarding to accommodate the crewmember.
Don’t make them get out of the seat!
During taxi, takeoff, and landing, flight attendants must remain at their duty stations with safety belts and shoulder harnesses fastened except to perform duties related to the safety of the airplane and its occupants.
This means that a flight attendant can and will leave their seat to address a passenger causing a safety problem in any phase of flight. Please follow the rules so the flight attendant doesn’t have to remove their seat belt during a critical phase of flight.
Special thanks to flight attendant and writer Sarah Steegar (@FATravelWriter) for the cabin crew seat belt info!
Pilot Seat Belts
At the top of the airline seat belt hierarchy is the pilot’s five-point harness. Like flight attendant seat belts, the pilot harness has two over-shoulder torso restraints.
Pilots have a fifth strap known as a “crotch” or “submarine” strap that comes up between the legs and attaches to the quick release.
In a high-speed crash, the submarine strap keeps the pilot’s torso from sliding forward and “submarining” under the lap belt and instrument panel. When used properly, the five-point harness allows pilots to control the aircraft in the most extreme situations.
Pilots are required to wear the lap belt at all times while in the seat. The crotch and shoulder straps must be worn during takeoff and landing. Many pilots unbuckle the shoulder straps after take off, then buckle them before landing or when moderate turbulence is expected.
Broken Pilot Seat Belt?
During our preflight inspection of the aircraft, the 5-point harness is one of the first things we check. If the restraint is not working perfectly, the aircraft is grounded. No exceptions. A maintenance engineer must fix or replace the harness.
Over the years, I’ve run into stuck buckles, worn straps, and shoulder straps that were unable to extend or retract.
The most unusual seat belt problem I have encountered:
While preflighting an aircraft that was fresh from heavy maintenance, I discovered that my 5-point harness had five male connector straps and no quick-release buckle. It took about 15 minutes for maintenance to replace the left-hand strap with a quick-release buckle strap. Good thing they had a spare in the parts warehouse!
The Seat Belt Sign
The seat belt sign is controlled by a switch in the cockpit. The sign must be ON for taxi, takeoff, and landing. Illuminating the sign during cruise is at the discretion of the captain. Individual airline policies vary. In general, if the aircraft is experiencing turbulence or expected to enter an area of rough air, the captain will turn on the sign.
Obviously, if the seat belt sign is ON, the flight crew thinks it’s pretty important for you to fasten your seat belt. What about when the sign is OFF?
When should you wear the seat belt? Always!
Recent accidents have demonstrated how effective seat belts are at saving lives. In 2013, Asiana Airlines flight 214 crashed short of the runway in San Francisco. The crash destroyed the Boeing 777, but resulted in only three fatalities. Two of the victims were not wearing seat belts and probably would have survived if they had. This is overwhelming evidence that modern seat and seat belt design is effective. Obviously, it’s important to wear a seat belt for takeoff and landing.
It’s also important to wear the seat belt any time you are seated, even when the seat belt sign is OFF. Turbulence during cruise can be a really bad deal.
What’s the point of a seat belt sign if the seat belt should always be worn?
When the seat belt sign is OFF, the captain is reasonably sure there is smooth air ahead.
This means it’s reasonably safe to get up and walk to the bathroom. On long flights, use the opportunity to stand and stretch once an hour to avoid deep vein thrombosis. As soon as you return to your seat, put the seat belt back on.
FREE for AeroSavvy readers!
Handy, wallet-size reference to remind you when to wear the seat belt.
Turbulence is caused when an aircraft flies through air masses moving at different speeds and/or directions. Uneven heating of the earth’s surface, mountains, high altitude jet streams, and even other aircraft can cause turbulence. Pilots can often “see” turbulent air by watching clouds. Fluffy clouds growing quickly on a summer afternoon is a clue that the air will be turbulent.
Clear Air Turbulence (CAT) can’t be seen visually or with electronic sensors (yet). Meteorologists issue advisories called SIGMETs (Significant Meteorological Information) that highlight areas of forecast turbulence. The seat belt sign will be on when flying near SIGMET areas. Sometimes we get surprise encounters with turbulence. For this reason, passengers should keep the seat belt fastened when seated.
Is the aircraft safe in turbulence?
Absolutely! No need to worry about the airplane. Airliners are designed to withstand forces far beyond what they will encounter in bad weather.
We do need to worry about stuff not strapped down inside. Every year, turbulence causes injuries to hundreds of passengers and cabin crewmembers worldwide.
Cabin crewmembers accept the risk of being injured by turbulence. It’s part of their job. Passengers can virtually eliminate risk of injury by keeping the seat belt on.
Turbulence Is Getting Worse
Dr. Paul Williams, Professor of Atmospheric Science at the University of Reading, published a study that indicates clear air turbulence (including severe turbulence) is increasing in response to climate change. His results suggest that transatlantic flights will be bumpier by the middle of this century.
Dr. Williams explains what’s happening in this CNN clip:
Kids and Seat Belts
Children under two can fly free if held in the lap of an adult. In a 2005 press release, the FAA reasons that if an infant rides for free, parents may be more likely to fly than drive a car. A child held on the lap in a plane is statistically safer than a child riding in a car. OK, so it’s legal to hold your kid on an airliner. But, should you?
Parent to Parent Talk:
Forget that I’m an airline captain who’s flown through a bunch of turbulence. I’m also the parent of four children. When our kids were under two, they always flew with full-fare tickets in FAA-approved car seats or child restraints.
The ugly truth about turbulence and lap children:
The force of severe turbulence can pull a child from an adult’s arms and bounce them off the ceiling. Isn’t that a pleasant thought?
Love is strong, but physics is stronger.
It’s not just me on this soapbox. Numerous safety organizations encourage the use of child safety seats:
- Federal Aviation Administration (even though they let kids ride on your lap)
- National Transportation Safety Board
- International Civil Aviation Organization
- American Academy of Pediatrics
- Centers for Disease Control
- Aerospace Medical Association
- …and many more
If you’re thinking about carrying your child for free, consider the possibility of him/her being injured in turbulence. Will the money you save be worth it? Buy your kid a ticket and use an approved car seat. Check the seat label for “FAA Approved.”
A Very Special Seat Belt: The AmSafe CARES Restraint
For little flyers between 22 and 44 pounds, AmSafe has a product called CARES: Child Aviation Restraint System. CARES is the world’s first and only alternative to using a car seat in an aircraft. The device is FAA approved for all phases of flight and can be used on any U.S. registered airline; both domestic and international flights. CARES is easy to use and weighs less than a pound.
We bought a CARES restraint a few years ago for our youngest child. He enjoyed using it and I highly recommend it.
Turbulence scares me. Should I still fly?
Of course! Flying is amazingly safe. In a chat I had with Dr. Paul Williams, he mentioned:
“Even if severe turbulence becomes twice or even three times as common in the future, as my research suggests, it will still be relatively rare. Double or treble a small probability and the result is still a small probability! Flying is the safest form of transport and nobody should not fly because of turbulence.”
Talking about airline safety is no different that learning about automobile safety or earthquake preparedness. Knowledge makes us safer. Chances are, your next flight will be enjoyable with only a minor bump along the way. Enjoy your peanuts and coffee!
Thank You to AmSafe
I’d like to thank the helpful folks at AmSafe for providing information and assistance.
AmSafe is the world’s leading provider of restraints for the aerospace and defense industries. Their seat belts are flying on over 600 airlines around the world. Next time you fly, check the seat belt label. Chances are, you’ll be wearing an AmSafe restraint!
AeroSavvy received no compensation from AmSafe.