as they stand massed in an unsecured part of a typical U.S. aiport.
And that is the biggest, most glaring, elephant-in-the-living-room hole in U.S. airport security. The last time I had the misfortune to go through Chicago O'Hare airport, there must have been 300 people packed into an area the size of a basketball court, all waiting to go through the TSA checkpoint. Never mind a nail bomb, the place was so packed that if someone had dropped a lit road flare, the panic and stampede would have caused casualties.
Not that I'm advocating dropping lit road flares in check-in lines, but if I can think of it, I'm sure someone else can.