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The North Korean MiG-17 pilots charged their guns and rolled in behind their target over international waters in the Sea of Japan. They believed they were attacking a P2V Neptune, but the subtle beauty and supple grace of the Lockheed patrol plane were missing in the sturdy hunk of blue iron that was cruising along in the MiGs’ gunsights. The aircraft the North Koreans were tracking was actually a P4M-1Q Mercator, built by the Glenn L. Martin Company in Baltimore.

In some sense, the Mercator was like the copilot sitting next to smallish pilot Commander Don Mayer on the plane’s spacious flight deck that day, June 16, 1959. Lieutenant Commander Vincent Anania was 6 feet tall, weighed 220 pounds and had been a varsity running back for the Navy football team. Anania often said that it took brute strength to fly the P4M-1Q, with its essentially mechanical controls. The Neptune had a gross weight of 64,100 pounds; the Mercator tipped the scales at 88,378. Crewmen gloated that you were forced to wriggle around in a crouch inside the Neptune, but even a 6-footer like Anania could stand fully erect inside a Mercator. A third larger than the Neptune, the Mercator was 100 mph faster—but also costlier.

That 1959 encounter between MiGs and Mercator was a memorable moment in the lives of Mayer and Anania, as well as my own life. At the time, I was an enlisted airman and language specialist at Osan Air Base in South Korea, monitoring the MiG-17 pilots’ chatter with ground control intercept as they began their attack on an aircraft many Americans had never even heard of. To this day, no one knows why the North Koreans attacked.

The Martin P4M-1 was created to lay mines during the invasion of Japan, but it would serve with just one patrol squadron before entering the sinister world of Cold War “black ops” reconnaissance as the P4M-1Q.

The Mercator was one of a handful of transitional airplanes powered by a mix of reciprocating and jet engines. Its two 3,250-hp Pratt & Whitney R-4360 Wasp Major radials were among the biggest and most complex piston engines ever put into the air. It also mounted two 4,600-pound-thrust Allison J33-A-17 turbojets. Each nacelle held one reciprocating and one jet engine. While the better-known Neptune had jets added to its two piston engines long after entering service, the Mercator was a prop-jet from the beginning.

The prototype XP4M-1 first flew on Sept. 20, 1946. (National Archives)

The Navy ordered two XP4M-1 prototypes on July 6, 1944. In its original incarnation, the Mercator was armed to the teeth. Its Emerson nose turret held two .50-caliber machine guns, swapped for twin 20mm cannons on production aircraft. The Martin deck turret on the dorsal spine bristled with two .50-cals, supplemented by two flexible waist guns of the same caliber. The Martin tail turret held two 20mm T-31 cannons. Armor plate protected the flight deck, and the windshield included sections of 2-inch armored glass.

The first XP4M-1 completed its maiden flight at Baltimore on September 20, 1946, with Martin’s chief test pilot and director of flight operations, O.E. “Pat” Tibbs, doing the heavy lifting. Martin built just 19 P4M-1s, the last rolling out the factory door in September 1950, shortly after the Korean War had begun.

The production P4M-1 first flew in September 1949. Patrol Squadron 21 (VP-21) at Naval Air Station Patuxent River, Md.— then equipped with Consolidated PB4Y-2 Privateers—took delivery of its first Mercator on June 28, 1950. Martin, busy building several other aircraft, including the 4-0-4 airliner, fell far behind Lockheed, whose less expensive but less capable Neptune equipped 13 squadrons and would eventually equip 20.

The Mercator began its only stint as a patrol plane at Port Lyautey, in French Morocco, with VP-21, searching for Soviet submarines. Naval aviators who served there after World War II recall the semitropical sun and bleak austerity of the airfield, which U.S. forces had seized from the Vichy French. The Soviet Union did not have half as many subs as Collier’s magazine had postulated at the time— 450—and VP-21 members do not recall ever coming across one.

When Mercator pilot Sam Linder arrived at Port Lyautey, he found the squadron confronting “a lot of aircraft maintenance problems. In particular, the jet engines had had blade failures in other applications in the Navy, so their use was restricted in the P4M. They were started and kept on idle for takeoffs and landings (emergency use only), and the aircraft had to do all of its principal flying with the recips only.” Later in the Mercator’s career, the jet engines were employed without restrictions. VP-21 operated 10 P4M-1s until it began giving them up for P2V-6 Neptunes in February 1953.

In 1950 the Navy began modifying the Mercator for electronic reconnaissance as the P4M-1Q. The new mission was to intercept and collect radar emissions from the air defense networks of the Soviet Union and its allies. The P4M-1Q could be readily distinguished from the P4M-1 by a chin-mounted “beard” fairing that contained radar-intercept gear.

Despite its mechanical complexities, the big, powerful Mercator was ideal for Cold War snooping. With an operational range of 2,000 miles, the P4M-1Q routinely cruised at 180 knots monitoring radar emissions. If threatened, the pilot could bring its two jet engines on line and accelerate to an impressive 340 knots, though of course it was still vulnerable to MiGs.

In October 1951, P4M-1Qs began operations from Sangley Point, in the Philippines, in a squadron eventually designated VQ-1. For the reconnaissance role the airplane’s 14-man crew consisted of pilot, copilot, navigator (who was trained as an aviator), electronics officer, six intercept operators, plane captain (who doubled as “relief” on the gun turrets) and three gunners. On February 7, 1952, the squadron lost a P4M-1Q piloted by Lieutenant Robert B. Rager, who ditched at sea following the failure of the port reciprocating engine. Eighteen crew members were rescued, but a Royal Air Force airman was killed when his Supermarine Sea Otter from Nicosia, Cyprus, crashed during efforts to save them.

VQ-1 relocated to Iwakuni, Japan, in 1955, and a second Mercator reconnaissance unit, VQ-2, was formed at Port Lyautey. Four P4M-1Q Mercators equipped each squadron, plus a stripped P2V-2 Neptune for crew training.

VQ-1 and VQ-2 crews were at the vanguard of a secret war in the 1950s, when spy planes gathered signals intelligence, tested the frontiers of the Communist world and routinely “tickled” air defense networks to gauge the enemies’ reactions. While reconnaissance is carried out more openly today, Mercator men lived in a world where their duties could not be admitted in public. In an awkward situation rectified on similar missions in later years, the older members of the flight crew up front did not have the same security clearance as the younger crewmen, often teenagers, working in the back. Until August 1956, these flying ferrets did not wear standard markings. The bureau numbers painted on the P4M-1Qs were bogus, and one pilot remembered, “We changed them once a month”—even though the Communists were aware of what the Mercators were doing and could have cared less about bureau numbers.

A little-noted fact about the Mercator is that its vertical stabilizer was slightly offset from the fuselage centerline to counter torque from the powerful piston engines. The huge R-4360 “corncobs” were a maintenance nightmare. VQ-1’s move to Iwakuni was made in part to co-locate the unit with two squadrons of Marine Corps Fairchild R4Q-1 “Flying Boxcars,” which used the same power plant, so that “the Navy could lump all of its R-4360 problems together in one place,” according to pilot Captain Norman S. Bull.

U.S. Navy Cmdr. Don Mayer and Lt. Cmdr. Vincent Anania were flying this Mercator on June 16, 1959. (National Archives)

There were instances when improper maintenance on the Mercator’s argumentative, 15-foot-1-inch four-bladed Aero Products propellers caused an engine to tear from its mount. This problem came to the fore during a June 15, 1955, reconnaissance mission along the Chinese coast, when the port recip fell completely off a P4M-1Q, throwing the heavy Mercator into a flat spin. “The prop was out of balance and it tore the engine off,” remembered pilot Lieutenant Jim Edixon. “It sounded like a 20mm [shell] going off inside the airplane.” Edixon noted that because of propeller torque, “had it been the right side, it would have torn the airplane apart.” Through quick thinking and skilled airmanship, he managed to recover from the spin at 3,000 feet with the aid of the jet engines.

On August 23, 1956, Chinese MiGs shot down that same P4M-1Q 32 miles off China near Shanghai. The Mercator was carrying four officers and 12 enlisted sailors. A Morse code message from pilot Lt. Cmdr. Milton Hutchinson read, “Under attack by enemy aircraft.” American aircraft and ships, including two carriers, participated in a search effort that eventually yielded the body of just one crewman, Petty Officer 1st Class Albert P. Mattin, plus two empty life rafts, a main wheel and two bomb bay fuel tanks. Three more bodies were eventually recovered. Family members believed then and now that Chinese forces captured some crew members, though no evidence to support that contention has ever surfaced.

On January 6, 1958, a Port Lyautey–based P4M-1Q belonging to VQ-2 crashed at Ocean View, Va., killing four crewmen and injuring two others. The fuselage opened up directly in front of radioman Tom York, who walked away from the wreckage unscathed.

Returning to the confrontation described at this article’s start, on June 16, 1959, Commander Mayer’s Mercator was jumped by two MiG-17s from North Korea’s 2nd Air Division. The P4M-1Q had flown a routine track the previous day over the Sea of Japan from Iwakuni to Misawa, Japan, identical in reverse to the track it was flying on the 16th. According to the after-action report, it departed Misawa at 8:08 a.m. local time, proceeding on “a northwesterly course at altitudes between 6,000 and 7,500 feet to a point over the Sea of Japan approximately one hundred miles off the coast of Siberia.” The Mercator flew its planned track in “westerly and southerly directions, roughly parallel to the coast, to the point at which the attack occurred.” For 25 minutes prior to the attack, “the P4M had been on a heading which would have taken it to a point on the Korean coast south of the demarcation line. Coincident with the beginning of the attack, the P4M was 78 miles east of Wonsan, North Korea, and commencing a left turn to a southeasterly course away from land.”

At 12:12 p.m. two “silver-colored MiG type fighter aircraft, bearing red star markings on the fuselage abaft the cockpit, appeared high astern of the P4M, already in their attacking runs. One MiG passed overhead without firing but the other opened fire on his initial pass, hitting the P4M on the port side. Employing standard fighter tactics, the MiGs made at least five passes, three of which were firing runs. On the second firing run, the P4M tail gunner [Petty Officer 2nd Class Eugene Corder] was ready but the MiG fired first, seriously wounding him and knocking his turret out of action.”

Corder was an electrician, not a gunner. He was in the aft position while the tail gunner, named Nelson, was elsewhere in the aircraft. Pilot Mayer sent a distress call, gave orders to open fire and dived to 50 feet above the water. The MiGs followed and “pressed home their attacks for approximately five minutes,” the official report stated. “After breaking off the last attack, the MiGs pulled straight up to a high altitude and disappeared to the north.” Fighters escorted the P4M-1Q to Miho, Japan. A squadron member recalled that “the extraordinary physical strength of copilot Anania helped keep the crippled plane airborne.” (Anania, incidentally, was the father of three children, including Elizabeth, who would grow up to become an attorney and the wife of U.S. Senator John Edwards.)

After VQ-1 retired its last P4M-1Q in a ceremony at NAS Atsugi, Japan, on July 2, 1960, Douglas A3D-1Q/2Q Skywarriors took over the Mercator’s mission. Sadly, though the rugged Mercator would have made a great museum exhibit, none survives today.


U.S. Air Force veteran Robert F. Dorr, who died on June 12, 2016, was a retired diplomat and the author of many aviation books and articles. Further reading: Martin Aircraft, 1909-1960, by John R. Breihan, Stan Piet and Roger S. Mason. This article originally appeared in the January 2015 issue of Aviation History magazine. For more great articles subscribe today!