Lobbying groups say that private flying helps produce pilots to feed the growing demand for airline crews.

Also eligible are "low risk" visitors like diplomats, airline crews and representatives of international organizations.

The controversy over whether or not airline crews are "radiation workers" is not new.

The radiation received by airline crews is from cosmic rays.

Sullenberger has also been studying the psychology behind keeping an airline crew functioning during a crisis.

So it sends a message to the public that, hey, they're checking everybody, including the airline crews.

Special rates have also been established to attract airline crews, according to the general manager, Larry Horn.

The witnesses, including two airline crews in the area, each described seeing the plane wobble before pieces fell from it.

There's a proper way to talk to the airline crew, he said: "The first rule is, you never hassle the pilot."

This most often happens when airline crew are located in the wrong place and need to travel to take up their duties (positioning).