By Pierre Kosmidis
Photos, text and research submitted by Dan Farnham, used by permission
Designed in 1937, the Martin ‘Model 162’ was the replacement for Martin’s earlier open-cockpit P3M flying boats, which had been in service with the US Navy since 1931.
The new Model 162 was a massive design and Martin built a quarter-scale, single seat model known as the ‘162A’ to test its flight characteristics. On June 30, 1937, the U.S. Navy ordered a single full-size prototype for flight testing. It was given the designation XPBM-1.
The first flight of the prototype was on February 8, 1939 and in December the U.S. Navy placed an order for 20 of the new planes and it was given the name Mariner.
PBM stands for Patrol, Bomber, and the ‘M’ was the letter assigned by the U.S. Navy to all aircraft built by the Martin Aircraft Corporation. The PBM had two engines, each with a three-bladed propeller, and the elongated engine nacelles also had room for four 500-pound bombs or depth charges, or auxiliary fuel tanks.
The wingspan measured 118 feet and it was just under 80 feet from nose to tail. Defensive armament consisted of six machine guns located in the nose, dorsal, tail, and waist positions on the aircraft.
Later versions of the Mariner had improved engines with a four-bladed propeller, and they could carry up to eight 500-pound bombs, depth charges, or mines in the nacelles. The Mariners could also carry two torpedoes under the wings of the plane. A total of 1,366 PBM’s were built until production ceased in April 1949.
VP-202 was the first PBM squadron to become operational in the Pacific. In early January 1944, VP-202 operated from Tarawa in the Gilbert Islands (today known as Kiribati) to patrol the Japanese-held Marshall Islands.
On February 6th, just two days after Kwajalein Atoll was declared secure from invasion operations, VP-202 arrived with the seaplane tender USS Casco (AVP-12). The ship and squadron set up operations at Ebeye Island, where the Japanese had built a seaplane base prior to the outbreak of the war.
On February 16th, a PBM-3D of VP-202 crashed on landing at night while returning from a sector patrol mission. The plane broke apart, burst into flames, and sank. Of the 11 personnel on board, six survived the crash and five were killed.
One of the pilots, LT (j.g.) Wilburne E. Piercy, was listed as missing-in-action following the crash. The wreckage of the plane, broken into several pieces, was found in the summer of 2009 by several Kwajalein divers, some of whom would later go on to help formally organize the Kwajalein MIA Project.
On March 11th, VP-202 rotated back to Kaneohe, Hawaii for repairs and crew rest. VP-202 returned to Kwajalein Atoll in June 1944, and provided daily mail flights between Kwajalein Atoll and Saipan. This was the only air contact with the outside world for the troops on Saipan during the early days of the invasion of that island.
In April 1945, VH-5 arrived at Naval Air Base Ebeye Island, and also had detachments at Majuro Atoll and Eniwetok Atoll. The squadron performed air-sea rescue, casualty evacuation, anti-submarine patrol, and various other duties.
After the Japan announced its surrender on August 15, 1945, VH-5 participated in the negotiations, formal surrender, and occupation by American troops of Mille Atoll and Jaluit Atoll. The squadron was disbanded in June 1946.
In September 1945, VPB-32 was transferred from the Atlantic and based at Saipan, establishing mail and passenger flights to Truk Lagoon, in the eastern Caroline Islands. VPB-32 formed detachments at several locations, including a detachment at Kwajalein Atoll.
In the summer of 1946, 15 PBM’s from VBP-32 and VH-1 were based at Naval Air Station Ebeye Island, and flew in support of Operation Crossroads, which was the nuclear weapon test series conducted at Bikini Atoll that summer.
The PBM’s carried mail, supplies, VIP’s, and performed technical missions including photography, radiometry, radiological reconnaissance, damage estimation, and air-sea rescue standby.
A typical PBM schedule was two flights per day, but extra flights were frequent. In September 1946, the VBP-32 detachment at Ebeye was transferred back to Saipan, where the squadron continued to operate until mid-1949.
VR-23 operated a detachment of PBM’s at Kwajalein Atoll in 1949, prior to being reassigned to the Phillipines and merged with VR-21. VR-23 performed similar cargo and passenger-carrying missions as previous PBM squadrons based at the atoll.
Over the years, besides the crashed PBM-3D from VP-202, three intact PBM’s have been found on the bottom of the lagoon, and parts of two more which were cut up and the pieces also disposed of in the lagoon.
The intact aircraft are missing their engines, props, and other equipment, indicating they were stripped of any usable gear before being scuttled. The three intact examples are a PBM-3R, a PBM-3D, and a PBM-5.
Based on information found in squadron diaries, there are two or three more intact PBM’s somewhere in the lagoon, although they have not yet been found.
A few PBM’s survive today in museums, but no museum anywhere holds more than one example of the plane.
With at least three intact versions of PBM’s lying on the bottom of the lagoon, Kwajalein divers have a unique look into part of the developmental history of the plane, which is not found anywhere else in the world.
Recommended additional reading:
The Fighting Flying Boat: A History of the Martin PBM Mariner, by Richard A. Hoffman, 2004, published by the Naval Institute Press
Foundation, Fall 2011 issue (semi-annual publication of the US Naval Aviation Museum Foundation)
X-Ray Dive Magazine, Issue #40, January 2011