Can a Crazed Jet Blue Pilot Break Down a Bulletproof Cockpit Door?

There’s always a bit of scaremongering that goes on with the genre of Crazy Airline Stories. Are our skies safe? What about the children? That kind of thing. So, in the story of the Jet Blue pilot, Clayton Osbon, who lost it this week and was restrained by passengers and crew, the LA Times says today that he “pounded so hard on the locked cockpit door that the first officer feared Osbon was breaking through the bulletproof barrier.” This sentence reads funny, on first glance! But the door is bulletproof, one thinks! Surely a non-bullet, then, can’t break down the door? Or can it.

Let us look at our post-9/11 bulletproof cockpit doors. The FAA guidelines say that door components have to be rated to withstand 2 impacts of 300 joules, at three different cockpit-facing points. And then the bolted door is rated for pulling force. Ooh, science!

For a sorta helpful comparison of what that means, a 9mm Luger has the muzzle force of, give or take, 470 joules. That’s less than really helpful, because a bullet is incredibly focused; that’s why bullets go through things and people, because the force is compact. And a person trying to break through a door is more distributed. (And the material used to make the door bulletproof doesn’t serve the same function as what makes the door difficult to break down.)

So let’s use another human motion: weightlifting, and its foot-pound force. The doors are rated for 221 foot-pounds by that measure. What’s that mean? If you look at the physic of weightlifting, the math says that, if you benchpress 250 pounds for eight reps over 48 seconds, that’s an expenditure of 208.3 foot-pounds per second.

For Boeing planes, which Jet Blue doesn’t use, let’s revisit what they said about their bulletproof doors: “The new door withstands bullets and small explosives and can resist a force equivalent to an NFL linebacker hitting it at Olympic sprinter speed.” Airbus doesn’t make that kind of grand (and kinda hilarious) claim, but they do also meet the FAA ratings.

A football tackle — mass plus speed! Inertia! The laws of physics! — can be 1600 pounds of force. (Lots more here on football physics! There’s a million variables.) But an object hitting an unmoving object is not quite easy to calculate, because the question of force relies upon: how much time passes during the impact? If a person were moving at 200 mph, and the impact took .01 seconds to transact, the impact would be significantly stronger. But then to achieve that speed, that person would have to be shot out of a cannon inside the airplane. Which seems unlikely, or at least complicated. (This is, of course, why people use battering rams on doors — they’re small enough to direct force, light enough to gain speed.)

So the problem for a disgruntled captain is actually getting up enough speed to create force and to minimize time of impact, so as to deliver force. If you had a really good run-up, definitely from at least the middle of first-class, and you didn’t break something in your shoulder on the first two impacts, it seems pretty likely that you could eventually definitely cause a hinge to snap on the cabin door. You might get really lucky on the first two attempts even! (Should, you know, you be allowed more than one chance.) But it seems at the very least highly unlikely that just banging your crazed ham-fists on the door is going to do the trick.