Since Robinette's first airline seat study for NASA and the FAA in 1978, she has a different perspective when she boards an airliner. "I always see all kinds of arms hanging out into the aisles. That means the seats are too narrow, and there's nowhere for the shoulders and arms to go except into the aisle because there's not enough room in the seat."

When "you keep getting your arm whacked by the cart as it comes down the aisle," don't feel guilty, she says. It happens to everybody. "And it's because of the seats."