The 747-100 was the programme's initial version: ordered by Pan Am in 1966, it first flew on 9 February 1969 and entered service on 22 January 1970 on the New York–London route.
Its maximum take-off weight and fuel capacity left it short for the longest intercontinental routes, a limitation the -200 corrected. From it Boeing derived the heavier -100B and the short-range -100SR, with a reinforced structure, for Japan Air Lines. 167 were built, and one of them served NASA as the Space Shuttle carrier.