That was the sales pitch when most observers thought the 747 was going to be the last subsonic long-haul passenger plane. "Don't worry about the supersonic pla

That was the sales pitch when most observers thought the 747 was going to be the last subsonic long-haul passenger plane. "Don't worry about the supersonic plane we're currently designing, you'll be able to sell your 747 as a great easy-conversion cargo plane once the SST comes out."