By now everyone has heard the sound bite from Flight 188’s First Officer Cole:

The first officer of the Northwest Airlines jet that missed its destination by 150 miles says there was no fight in the cockpit, neither he nor the captain had fallen asleep and the passengers were never in any danger.

But in an interview with The Associated Press two days after he and a colleague blew past their destination as air traffic controlled tried frantically to reach them, pilot Richard Cole would not say just what it was that led to them to forget to land Flight 188.

So just what was it?