Why Your Plane Can’t Have An Escape Pod
Recent terrorism alerts may put the flying public on edge. But not every would-be solution ought to get off the ground.
Terrorism fears prompted the United States government to issue a rare (and infuriatingly unspecific) worldwide travel alert yesterday. Assuming the world is not anxious to spend more time waiting in line to have their belongings X-rayed, is there any way to make planes themselves safer from terrorists? Yes. But some technological solutions aren’t worth the cost.
Case in point: in 2012, Tetyana Ivanivna Demenchuk, a Ukrainian designer, patented a novel means of keeping passengers alive as a plane goes down. Here’s how it works: say someone targets your plane with a Russian Buk missile , or there’s a double-engine flameout, or some other unthinkable and highly unlikely event occurs and your plane begins to fall out of the sky. Demenchuk’s system ejects you and the rest of the passengers out the back of the fuselage in a hermetically sealed capsule. It’s basically a plane within a plane.
This video explains shows how it works.
In theory, it’s not unlike the escape systems for some manned spacecraft. But the small explosives that might pull a capsule from a malfunctioning booster rocket wouldn’t be safe in commercial flight. So Demenchuk’s patent calls for tubular guides (or rails) and special motorized devices to push the escape pod out the open bay doors.
Computers aboard the capsule, which essentially becomes a new aircraft, detect its position in space and control the parachutes. The humans aboard would somehow be strapped down via “individual means for cushioning and fixing the safety of passengers and crew members at the time of landing or splashdown,” according to a translation of the patent. Of course, a capsule large enough to carry that many passengers would be incredibly heavy, and so a set of booster rockets would ignite to slow its final descent.
Would it work? Similar concepts have performed well for small aircraft. So-called ‘parachute saves’ of planes like the Cirrus SR-22 have become so common that The Atlantic’s James Fallows can write about them multiple times in just a few months.
To David Akin, director of the Space Systems Laboratory at the A. James Clark school of engineering at the University of Maryland, Demenchuk’s design seems to build upon some of the ideas that the space community was entertaining after the Challenger shuttle explosion in 1986. “After Challenger the question was how to protect the crew in the event of something like that happening again. They looked at things like ejection seats, pods, and ejecting the entire crew,” he said.
The military has experimented with some similar systems for jets. The Convair B-58 bomber and the North American XB-70 had capsule pods that protected the crew when they ejected, according to Akin. “The initial version of the [Rockwell] B-1 bomber had the entire crew cabin come off together. That was probably the most feasible of the ideas that they looked at for the shuttle. The entire capsule came out on rocket thrusts. But you could only fly four crew,” he said.
But the feasibility of Demenchuk’s design is limited at best. “Is it physically feasible that you could do this? Sure. If you wanted to bad enough, you could,” said Akin.
What may make sense for crew of astronauts on a rocket that will destruct once or twice every hundred flights makes no sense on a passenger jet with a great safety record. “The bottom line was to do something like that [on a NASA Space Shuttle], you lost all the payload capability of the spacecraft because all the weight went into the safety system. Think about this is a safety system for a commercial airliner. You’re cutting the number of passengers you can carry in half because of all the safety system.”
Kit Darby, an airline consultant and former pilot, acknowledged that it didn’t appear to be outside of the capabilities of physics, but such a system would be economically and practically unrealistic, offering too little in safety for great cost for passenger aircraft.
First of all, Darby said, “I know that there’s going to be additional weight [with the system]. Fuel is the largest single expense for an airline. For every pound that you carry, you burn five percent of it an hour just to carry it. It’s very inefficient to add weight.”
But what’s a few extra bucks, and refueling stops, when lives can saved, right? Not if the concept, as designed, would be useful only in the rarest of circumstances. “The number of times that you would actually need to get out of the airplane is extremely small. When I look at it from the perspective of a pilot, the safety you gain from the very, very few times when the airplane would become uncontrollable — I mean there are hardly any of those.”
It also solves the wrong problem in Darby’s view. Planes are much more likely to crash upon takeoff or landing — that is, at low altitude — than in midair due to massive mechanical failure (or being shot out of the sky) altitude. “Parachuting doesn’t work well during takeoff and landing,” says Darby.
Demenchuk’s concept leaves the biggest problem on the table: planes are still flown by humans and human judgment is the weak spot on plane safety.
“I’m not sure how this corrects for pilot error, but the system doesn’t prevent the error,” he said.
In fact, the presence of another big red lever to pull may increase the likelihood of a fatal pilot mistake, according to Akin. “You have to be careful you don’t cause an accident because of an inadvertent actuation of the safety system. It’s an accident that wouldn’t happen without that safety system. Then consider ejection seats on military aircraft. You have a certain non-negligible chance of dying in an ejection process. It’s there in case there is no other solution.”
Just remember that the next time you’re having your shoes x-rayed.