SAM 26000 was replaced in December 1972 by another VC - 137 , Special Air Mission 27000 .
SAM 26000 was kept as a backup until it was finally retired in 1998 .
SAM 26000 was replaced in December 1972 by another VC - 137 , Special Air Mission 27000 , although SAM 26000 was kept as a backup until it was finally retired in 1998 .