5 Facts About The Martin P4M Mercator; Forgotten Snooper

The Martin P4M Mercator was a land-based maritime patrol bomber and reconnaissance aircraft to replace the PB4Y-2 Privateers but lost to the Lockheed Neptune design. Still, it managed to have a successful, decade-long career as a spy plane for the US Navy.

1. The Martin P4M Mercator is a little bit of an oddity

It was built in small numbers and started life as a failure. In 1944, the US Navy put out a replacement for the Consolidated PB4Y-2 Privateer, but not as a specialist reconnaissance platform. Rather, the Navy wanted to produce the next generation of long-range maritime patrol aircraft. Martin got to work to develop the aircraft the Navy wanted, with exceptional range, carrying capacity, and toughness, all combined with an excellent sprint speed for getting into and out of trouble.

However, by the end of WWII, the Navy decided they could settle for something less extravagant for their maritime and anti-submarine patrol plane and chose the Lockheed P-2 Neptune instead. The need for the Mercator became largely redundant. Still, the US was aware of how potent the aerial mining campaign against Japan was in that final year of the war and decided it was worth keeping. Thus, in 1947, it made a limited order for 19 of the big aircraft.

2. In 1951, the Navy started converting the P4Ms into signal intelligence aircraft

It was something that the Mercator’s big frames, high power, and excellent range were ideal for. This alteration also saw a massive secret monitoring equipment added and the crew size expanded to 16, mostly made of specialists that monitored the advanced electronic listening gear.

3. It was eventually redesignated as P4M-1Q, doing secret flights operating from the Philippines and Japan

It conducted eavesdropping missions along Korea, Vietnam, China, and the Pacific Coast of the Soviet Union.

4. The Mercator’s visual similarity to the Neptune, then the Mainstay US Maritime Patrol Aircraft, meant that Mercators were often disguised as smaller planes

It used the markings and insignia of conventional squadrons to hide their nature from snoopers and enemy intelligence officers.

5. Not a single Mercator was preserved

Despite the importance of the work they conducted during the early years of the Cold War (or maybe because of it,) not a single Mercator was preserved. All of them were scrapped after they retired.