747-300M

The 747-300M is a Combi built on the 747-300 airframe: freight in the rear of the main deck behind a movable partition, passengers forward, and a side cargo door behind the wing — the same arrangement as the 747-200M, but with the stretched upper deck.

21 were delivered.

Why the stretched upper deck helped a Combi more than anyone

On a Combi, main-deck floor space is the thing being fought over. Every pallet position aft is a block of seats you cannot sell.

The stretched upper deck changes that arithmetic. It adds roughly 44 seats’ worth of cabin above the main deck, in a space that cargo can never use. So on a -300M the seats displaced by freight are partly recovered upstairs — which is why a -300M carried meaningfully more passengers than a -200M with the identical cargo load.

That is a neat illustration of why the SUD mattered commercially, and not just visually.

Operators and fate

The -300M went to airlines running routes with strong cargo demand and moderate passenger numbers — the same logic that drove every 747 Combi. KLM was the archetypal Combi operator across the whole family.

The configuration is now extinct in passenger service. The main-deck cargo compartment on a Combi sat on the same deck as passengers, and after the loss of a 747-200M to an in-flight cargo fire in 1987 regulators tightened fire-suppression requirements considerably. The cost of compliance, combined with the general shift to dedicated freighters, ended the layout.

Related

• The 747-300, the base aircraft
• The 747-300SR, the high-density domestic version
• The 747-400M, the last and most numerous Combi