Where was president Nixon when Gerald Ford assumed the presidency?

Nixon was aboard Air Force One when Ford was sworn in as President of the United States, en route from Andrews Air Force Base to California. Check this out:

http://www.af.mil/news/Aug1999/n19990809_991486.html

A great question, and I enjoyed researching its answer.

I've read elsewhere that the plane had to change it's call sign en-route to California. Since his resignation was effective at noon on August 9, the pilot had to have the course and time plotted, and found that the plane was crossing a state line at that time. I was hoping someone could answer that as well, it's the one part of the story I'm not sure of.

Mahal, you are correct...At the exact moment of Gerald Ford's swearing in, AirForce One became its mormal AF numeric call sign....At that moment, Nixon became an ordinary citizen....
I have never heard of crossing a state line at that moment....