Why Did Boeing Build The 747 With Only A Partial 2nd Deck?

The Boeing 747 is one of the world’s most iconic planes, and it is easily recognizable thanks to its frontal hump, which often contains a luxurious lounge or additional seating in passenger variants. It is an old bird, having first been delivered with what became Pan American World Airways in January 1970, but the most recent passenger variant of the massive quadjet, the 747-8 only recently ceased production. The final aircraft was delivered to Atlas Air in January 2023.