WASHINGTON — At one time, airline safety generally meant one thing: avoiding a crash. But safety regulators are increasingly focusing on surviving one.
Starting this Autumn, all new airplanes will be required to have seats that will stay in place when subjected to stresses up to 16 times the force of gravity. The old seats had to meet stresses of only nine times the force of gravity. And, in a safety measure borrowed from automobiles, some seats will be equipped with air bags.
The combination of sturdy seats and air bags means that if a plane touches down short of the runway or rolls off the end of the runway and hits an obstruction, “You’re going to be conscious. You’re going to have the opportunity to survive,” said Bill Hagan, president of AmSafe, which makes the air bags.
In some airline crashes, the strength of the seats is irrelevant because the crash is not what the engineers call “survivable.” In other crashes, still violent but not as much so as exploding in midair or breaking up in flight, the passengers’ survival depends on suffering little or no injury in the first phase of the accident, as when a plane runs off the runway, and then getting out of the plane quickly to avoid a postcrash fire.
The new rules have taken effect gradually. Airplane models introduced after 1988 were required to have the new seats, known as “16g” seats. So planes like the Boeing 777 and the swarm of new regional jets all have them. But older models that were still in production were not required to have the seats.
The air bags borrow technology from automobiles. They are set off by a shock meter that comes directly from cars. And like the systems used in cars and trucks, the seat belt air bags in planes are designed not to deploy inappropriately — in cases of air turbulence, for example.
In fact, said Mr. Hagan, this is simple, because the air bag sensor system watches for shocks on the axis on which the plane is traveling; it does not monitor up-and-down or side-to-side movements of the kind produced by turbulence, he said.
The air bags are widely used in first- or business-class cabins, where the seat in front is too far away or angled in such a way that it cannot function as a cushion. In coach class, the air bag has started out for use in front rows, exit rows and bulkhead seats, near galleys or toilets. In other seats, the passenger gets some protection from the seat back directly ahead, which is designed to break in a controlled fashion, providing a cushion.
Singapore Airlines flies 777s with wide intervals between seats and uses the air bag, JAL, Cathay Pacific and Virgin also use them.