VC-137C SAM 27000
SAM 27000 is the second of the two Boeing VC-137C aircraft that were specifically configured and maintained for the use of the president of the United States. It used the call sign Air Force One when the president was on board, and at other times it used the call sign SAM 27000 (spoken as 'SAM two-seven-thousand'), with SAM indicating 'Special Air Mission.' The VC-137C serial number 72-7000 is a customized version of the Boeing 707 which entered service during the Nixon administration in 1972.