Air Force One is the official air traffic control call sign for a United States Air Force aircraft carrying the President of the United States.
Any aircraft carrying the US President will be referred to as “Air Force One” and it ceases to be Air Force One if there’s no president inside.
Now, it so happened back in 1974 that President Nixon was flying on Air Force One when President Ford who was on the ground was sworn in as the next president. Since Nixon was no longer the president, Air Force One ceased to be Air Force One (No, it didn’t vanish into thin air though XD), its call sign was changed to SAM 27000.
So, technically it was not Air Force One that landed. Therefore, one less landing than the take offs.