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

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_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_Administration 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.