Was it legal for LBJ to be sworn in on air force one?

Yes, it was legal for Lyndon B. Johnson to be sworn in on Air Force One. The U.S. Constitution does not specify the location where the presidential oath of office must be administered, allowing for flexibility in extraordinary circumstances. Johnson was sworn in shortly after the assassination of President John F. Kennedy on November 22, 1963, to ensure a smooth and immediate transition of power. The event was conducted by federal judge Sarah T. Hughes, making it a legitimate and recognized transfer of presidential authority.