Why do car seatbelts have one strap whereas airplane pilot seatbelts have two straps?
In: Engineering
Car seat belts are optimized to reduce injuries in case of a crash.
Pilot seats are made to keep the pilot in his position at any cost, even in a falling and wildly spinning plane.
Cars travel on one planar field of motion. One strap.
Planes travel on two. Two straps.
Think about it
Pilot harnesses are actually a 5-point harness; there’s a strap that comes up between the legs, with a 4-part buckle assembly, and then a lap belt (L and R straps) and two shoulder straps (L and R) go into that.
You find this same sort of harness in the seats of high-speed race cars.
The use-case is the same: keep the person/people in control of the vehicle firmly in place despite the extreme forces exerted on them trying to pull them out of their seats in some extreme conditions that either may (pilot) or will (racecar driver) occur in normal operation.
Comes down to how you are most likely to die.
You are very likely to survive the plane crash. You are less likely to survive the ensuing fire, and will probably die of smoke inhalation.
A complicated seatbelt is the last thing you need as your skin melts and your lungs fill with carbon monoxide.
With car seatbelts, they are designed to keep your head from smashing through the steering wheel and into the dashboard. That kind of thing is pretty fatal most of the time. Cars usually don’t catch fire and explode after a crash. Which is why seatbelts in cars are designed to save you from the collision most likely to kill you (the one with the dashboard).
Car self belts are meant to protect you in a crash.
Airplane seat belts is just there so when there’s a crash, the police can identify the bodies if they’re seated at the right place