Many years ago, the T.V. spy series entitled "The Man from U.N.C.L.E." devoted an episode to the idea of using a model aircraft for delivering explosives and other noxious substances to sensitive places. So who needs an airport? Who needs a man carrying aircraft? Electronics are incredibly more sophisticated now than they were when The Man from U.N.C.L.E was made so all you need is model making skills, and a suitable explosives carrier can be made in your garage or basement. No problem to a determined terrorist! Also, will you get a primary radar return from a model?
Food for thought!