Crack-detectives foil aircraft failure: Detecting flaws in aircraft is based on nondestructive testing with new interpretive aids on the way

Anyone who has occupied the window seat of a commercial plane has probably watched the way the wing moves up and down — slowly, like a majestic bird in unhurried flight. This isn't necessarily unnerving, so long as the “flapping” remains reasonable. Aircraft wings are supposed to bend, the way tall buildings sway. If they didn't, they'd break. But when the plane runs into turbulence and the wings start to flutter — you wonder. How much is too much? After ail, metal fatigue is real.