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Comment by slimsag | Hacker News Reader

I get where you are coming from. I don't think that having x-ray detectors for plane luggage gives the passengers much safety: they could always use whatever weapon/bomb at the security line anyway!

I do, however, think that it's important not to let those people onto planes in contrast to buses, street corners, etc. because otherwise someone might take control of an entire plane, which can do a lot more damage than a bomb/pistol/etc, you know?

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In fairness, you can kill more people with a smaller bomb by detonating it in flight than just about anywhere. This is simply because airplanes are dense with people and very delicate. Given the cheapness and minimal passenger disruption from x-ray inspection of checked baggage, it seems like a no-brainer.

How much damage is done to searched bags, and how many items have been stolen by the searchers? More or less than the damage a terrorist would cause? I'm trying to say that searching bags is more expensive and more disruptive than you are trying to argue

That's a hard sell. I'd rather have luggage regularly stolen outright than perish in a plane crash. Luggage and lives are hard to compare.

I'd rather not die in a car crash, but that doesn't mean I'd pay an extra $10,000 for a car that reduced the risk of dying in a crash by 1%. You can't avoid putting an effective price on life, and in the US it's about $10 million.

Well, first note that you have to compare the current costs of scanning to the counterfactual where there is no scanning and terrorists know it. I'd wager we'd have at least a few bombing per year. (Planes seem to be a high-visibility target, and the US gets various random bombings on a yearly basis.) The cost of a downed passenger plane is of order $2 billion, using the statistical value of $10 million per life in the US.

https://en.wikipedia.org/wiki/Value_of_life#Life_Value_in_th...

The TSA's annual budget is $7.5 billion, of which only part gets spent on checked baggage screening.

https://en.wikipedia.org/wiki/Transportation_Security_Admini...

So those are some very rough numbers, but I think they will come out favoring screening. I'd be very interested in the calculation if you'd like to try to be more exact! The hardest part will be estimating the counterfactual bombing rate, but I bet the FBI has expert estimates of this somewhere.

This is what locked cockpits are for, not invasive luggage searches.

Interesting point; are there protocols in place to prevent a terrorist on board a plane from entering the cockpit at all costs? e.g. if they start executing passengers, threaten to blow up the plane, etc?

The cockpit doors have been locked since Sept 12, 2001. It is impossible to open them from the outside without very heavy machinery that could not be operated by a passenger, and even then it can take over half an hour.

Even if we did away with security entirely and let people carry guns on board, there would be literally zero risk of a hijacked plane in the US thanks to the locked doors. (There might be other reasons not to do that, but hijacking fears are not one of them).

And even then, it's arguable that this would still be impossible. 9/11 happened because hijacking protocol never took into account the possibility that the hijackers would use the plane itself as a weapon. The people on the final hijacked plane on 9/11 did know this, because they received calls about the WTC, so they fought back and forced the plane to crash, thwarting the hijackers' plans.

It may be mandated, or company policy, but ultimately it's up to the pilots. Cockpits seem to have quite a bit of security since 9/11[1], with the ability of crew to enter after a 30 second delay if there is not a denial by someone within the cockpit, and the doors are supposedly rated to withstand a grenade.

As we've seen, a plane can be devastating when used as a weapon, so I think it is sensible to deny terrorists to the cockpit at the expense of the passengers. Theoretically, there are few situations where passengers can be forcibly restrained, since they should outnumber any people trying to seize the plane by quite a bit, passengers could (and have[2]) attempted to neutralize the threat themselves (as they understand the possible consequences of waiting out the situation in this era where the goal is not money, but chaos).

1: http://www.bbc.com/news/blogs-magazine-monitor-32070528

2: http://www.cnn.com/2004/US/07/22/911.flight.93/

What happens when the pilots need to use the bathroom? This has always bothered me when people talk about reinforced cockpit doors as a cure-all for hijackings.

I think if the alternative is a psycho/collection of psychos gaining access to the cockpit, a puddle/pile on the floor is a reasonable outcome in that situation.

The cockpit door has a peep hole, and loitering near the front of the plane seems to be prohibited by most US air lines.

In addition, there is a protocol for this. The pilot will contact the flight attendant working in the front of the plane. The flight attendant will lock a beverage cart in front of the bathrooms, creating a (heavy, but not immovable) barrier between the cockpit and bathroom, and the rest of the plane. The flight attendant stands behind the cart, watching the passengers. The pilot looks through the peep hole, and when it is clear, comes out, locking the cockpit door behind him/herself. After using the rest room, the pilot knocks on the door to ask the copilot to open it. The peep hold is used to be sure the flight attendant is still standing guard and everything is normal.

There are obviously some risks here, as the door is opened briefly twice, but there are a number of steps taken to minimize this risk.

I'm curious - is this a 'known and standard' protocol adopted universally across many airlines? Or how do you know this? I guess I'm thinking that if this is 'known and standard' it may also be possible to design an attack against it.

There are some tweaks from airline to airline, but anyone who flies regularly has seen this general outline of events occur countless times.

An attack can be designed against any vulnerability. Whether that attack becomes practically executable remains to be seen.

There are obviously some risks here

The biggest realized risk seems to have been Germanwings Flight 9525. A suicidal co-pilot waited until the Captain left the cockpit. Then he locked the door and flew the plane into the side of a mountain.

https://en.wikipedia.org/wiki/Germanwings_Flight_9525

This introduces a new risk, that of sabotage by airline personnel themselves. As in the case of the Germanwings intentional downing by what's now thought to be a mentally ill co-pilot. He'd locked the captain outside the cabin.

Protocols to ensure two crew members in the cockpit at all times are now being considered.

There was an exceptionally good essay on implications of this incident, with computer/systems security implications, though I cannot locate it. James Fallows' Atlantic piece was good, though not quite what I was looking for.

http://www.theatlantic.com/international/archive/2015/03/ger...

Interestingly, the "two people in the cockpit at all times" rule was already law in the United States before the Germanwings incident.

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