We keep going and going and going and going

This one's quality reassurance, you can smell it. The uncertainty around on the use of the airplane. It's by numbers they gain reassurence, ever see a car with 1 billion miles on the road? Not likely. Don't even think anyone had enough time to drive non-stop to get to one billion in an automobile at the time. Even today that would be a bit much to swallow in for a trucker, or a transporter who drove nothing but Ferrari.
That would be back and forth accross the entire U.S. two hundred and fifty thousand times.

"Feel certain about that aircraft yet? Good, we all put a plug in below for the airline you'll now be using. Have a nice day."