Did you know that any aircraft that carries the President from a 747 to a Cessna 152 is Airforce 1 on the radio
That is true only of the Cessna is operated by the Air Force.
BTW the rest of the lineup is:
A2 - VP on Airforce a/c
A1F - First Lady on Airforce a/c
A2F - Wife of VP on Airforce a/c
Therefore Laura bush on a private or commercial flight would be operating as, "Executive one foxtrot..."