Martin Model 130
by Jack McKillop
The Glenn L. Martin Company
See Martin PBM.
The Model 130 was a four-engine, commercial high-wing monoplane flying boat. The crew varied from four to eight (the captain, two pilots, a junior pilot, flight engineer, radio operator and two stewards) depending on the distance flown. Only three aircraft were built and they were initially powered by four 830-horsepower Pratt & Whitney R-1830-S2A5-G 14-cylinder, twin-row, supercharged, air-cooled radial engines. Subsequently, they were re-engined with 950-horsepower R-1830-S3C3-G engines with Hyrdomatic propellers. The aircraft was of all-metal construction except for the fabric trailing edge. It had a two-step double-bottom hull, with upper sections constructed of corrugated duralumin sheeting. Sponsons, sometimes called “sea wings”, were fitted to the hull sides at cabin floor level. These airfoil-shaped surfaces fulfilled a dual function; they helped to stabilize the airplane while resting or maneuvering on the water and also served as fuel storage for nearly half of the flying boat's 3,800 U.S. gallon (3,164 Imperial gallon or 14,385 liter) fuel load. Retractable platforms were built into the leading-edge of each wing on either side of each engine nacelle, to provide access for servicing the engines—two of which were completely changed every three trips.
Aft of the flight deck, in order, were the galley, forward passenger compartment, lounge/dining room, two rear passenger compartments and a bathroom. Each passenger compartment could accommodate eight seats or six sleeping berths, and the lounge seated 12. While the M-130 could accomodate up to 32 passengers, the long distance payload between California and Hawaii was only 12 passengers. When taken over by the U.S. Navy in 1942, the interior was stripped and seats for 46 people were installed.
On 15 August 1931, Pan American Airways (Pan Am) issued a specification for a long-range flying boat to American aircraft manufactures. The specification called for an aircraft to carry a crew of four and at least 12 passengers over 2,500-miles (4,023-kilometers) at a cruising speed of 145 mph (233 km/h). Two companies responded, the Sikorsky Aviation Division, United Aircraft & Transport Corporation of Bridgeport, Connecticut offered their S-42 flying boat and Martin offered the Model 130. On 30 November 1932, Pan Am signed contracts with Martin and Sikorsky for three aircraft each. The three Model 130s were built in 1935/1936 and fully equipped, the M-130s cost US$417,000 each (US$7.1 million in 2013 dollars).
Beginning in 1929, Pan Am began investigating all possible air routes across the Atlantic Ocean to Europe. However, the British government blocked Pan Am's use of intermediate bases in Newfoundland and Bermuda until a British airline could be made ready for reciprocal service—a desire that never materialized. So, Pan Am turned its attention to the Pacific. Survey flights to Asia had begun in 1931, when Colonel Charles A. Lindbergh and his wife, Anne Morrow Lindbergh, made a flight along the Great Circle route from New York to Nanking, China, via the Arctic. Though successful, their epic journey exposed insurmountable challenges, both diplomatic and meteorological. Therefore, it was in the middle latitudes that Pan Am would create the first transpacific route.
The first M-130 to be delivered was named China Clipper, manufacturer’s serial number (msn) 558 and registered NC 14716, was delivered to Pan Am on 9 October 1935. The aircraft was flown across the Atlantic Ocean on a test flight in October and was then ferried to the Pan Am terminal in the yacht harbor on Alameda Island, California in San Francisco Bay on 11 November.
On 22 November 1935, the China Clipper inaugurated the world’s first trans-Pacific air mail service from the U.S. to the Philippine Islands. The plane carried 58 bags totaling 110,865 pieces of mail that weighed 1,837 pounds (833 kilograms). On that day, 125,000 people watched the plane take off from San Francisco. The flying boat service between the Pan Am base on Alameda Island in San Francisco Bay and Cavite in Manila Bay, Luzon, Philippine Islands required approximately 60 hours of flying time over six days with intermediate stops at Pan Am bases at Pearl City Peninsula, Pearl City, Oahu, Territory of Hawaii; Sand Island in Midway Atoll; Peale Island in Wake Atoll; and Sumay on Guam, Mariana Islands. The Clippers would fly between the five bases during the day and the crew, and later passengers, would rest in the local hotels during the night. Pan Am had built a 4-star single story, 45-room hotel on Sand Island, Midway Islands and Peale Island, Wake Atoll; both were known as PAAVille. The hotels featured solar water heaters, screened verandas, ceiling fans, handmade wicker furniture, an art deco dining room, bridge tables, beach umbrellas, tennis courts plus other amenities. There was no water on Wake Atoll so a water distillation plant had to be built.
China Clipper arrived at Cavite on 29 November and on their return trip, carried 98,000 letters back to Alameda arriving on 6 December. Perhaps most famous out of the first crew who flew this route was Fred Noonan the navigator, who would later disappear somewhere in the Pacific with Amelia Earhart in July 1937. The journey had taken 59 hours and 48 minutes flying time, and had traversed 8,210 miles.
On 14 November 1935, the second M-130, Philippine Clipper, msn 557, registered NC 14715, was delivered to Pan Am and was followed by the Hawaiian Clipper (later renamed Hawaii Clipper), msn 556, registered NC 14714, delivered on 30 March 1936.
Pan Am wanted to fly from Cavite to the British possession Hong Kong and in March 1936, the local authorities permitted cargo flights. Passenger flights from both Hong Kong and the Portuguese colony of Macao became effective in April 1937. Initially, the Cavite-Hong Kong service was flown by a Sikorsky S-42B but it would be more efficient if the Model 130s made these flights in 1938.
Pan Am was authorized to carry passengers in late 1936 and the Hawaiian Clipper took off from Alameda on 21 October 1936 for Cavite. The one way fare from Alameda to Cavite was US$799 (US$13,425 in 2013 dollars). The aircraft returned to the U.S. on 4 November.
In 1938, Hawaii Clipper, as Trip 229, disappeared with a crew of nine, six passengers and 1,138 pounds (516 kilograms) of cargo while en route from Guam to Cavite. The aircraft departed Alameda on 23 July 1938, the flight arriving at Honolulu the next day. The flight continued via Midway and Wake and arrived on Guam at 05:55 Greenwich Mean Time [GMT, now Coordinated Universal Time (UTC)] on July 28th or 15:55 Guam time. The aircraft departed Guam at 19:38 GMT (03:39 Manila Time) on 28 July, the aircraft actually leaving the water 29 minutes later.
At 04:11 GMT July 28th (12:11 Manila Time), the following 04:00 GMT position report was received by a radio operator on Panay Island, the Philippines, from the Hawaii Clipper:
Flying in rough air at 9,100 feet (2,773 meters). Temperature 13 degree Centigrade (55 degrees Fahrenheit). Wind 19 knots per hour (22 mph or 35 km/h) from 247 degree. Position Latitude 12 degree 27 minutes North. Longitude 130 degree 40 minutes East dead reckoning. Ground speed made good 112 knots (129 mph or 207 km/h). Desired track 282 degree, Rain. During past hour cloud conditions have varied. 10/10ths of sky above covered by strato cumulus clouds, base 9,200 feet (2,804 meters). Clouds below, 10/10ths of sky covered by cumulus clouds whose tops were 9,200 feet (2,804 meters). 5/10ths of the hour on instruments. Last direction finder bearing from Manila 101 degree.
The 04:00 GMT position report indicates that the aircraft was about 670 miles (1,078 kilometers) east-southeast of Manila.
The radio operator on Panay Island acknowledged this message and indicated that he wished to transmit weather sequence reports based on observations complied at 04:00 GMT by the Philippine Stations and relayed to him in accordance with Company procedure. The radio operator on the Clipper replied as follows: “Stand by for one minute before sending as I am having trouble with rain static.”
The radio operator in Panay again called the Clipper at 04:12 GMT, giving him the weather sequences. This message was not acknowledged. The radio operator on Panay continued calling the Clipper until 04:15 GMT, at which time he sent the Clipper’s 04:00 GMT position report to Manila. At 04:35 GMT, the Communications Superintendent, Pacific Division, in Alameda was notified of the failure of communication between ground stations and the Clipper. All Philippine stations were requested to stand by on emergency frequencies at 04:49 GMT. This is standard emergency procedure whenever an interruption of communication happens between shore stations and the aircraft. Interruptions do occur from time to time and often there is no alarm, the emergency procedure is put into effect as a matter of routine.
An intensive search over a large area of the ocean was conducted by the U.S. Army transport USAT Meigs, Navy destroyers and submarines, and by Army and Navy aircraft. Other surface vessels in that part of the Pacific lent their assistance. A search of the shores and interior areas of Luzon and Mindanao Islands, and other smaller islands of the Philippines group, was conducted by Army bombers and Navy ambitions but not a trace of this aircraft was ever found.
In 1937, a project began to build a man-made island in San Francisco Bay for the 1939-1940 Golden Gate International Exposition and a base for Pan Am. Following the Exposition, the island was to become San Francisco's municipal airport. The island was named Treasure Island.
Construction included a terminal building with two hangars on the south side of the island and an airfield on the northern end. On 23 January 1939, Pan Am moved to new quarters on Treasure Island from Alameda Island. Pan Am's operation was a part of the Exposition and featured a spectator's gallery in one of the hangars to view the airline's maintenance and overhaul work.
Aircraft of the Imperial Japanese Navy attacked numerous U.S. military installations on Oahu, Territory of Hawaii, beginning at 07:55 Hawaii time, 7 December 1941. Wake Island was west of the International Date Line so that was 04:25, 8 December on Wake. The Philippine Clipper, which had spent the night of 7/8 December at Wake, embarked passengers shortly after sunrise, taxied out into the calm green of the lagoon, took take-off position, and at 06:55 Wake time soared outward toward Guam. In the U.S. Army Air Corps’ Army Airways Communications Service radio van set up near the air strip, an operator was coming up on frequency with the base at Hickam Field on Oahu, when, at 06:50 Wake time, a frantic uncoded, procedureless transmission cut through from Hickam: “Oahu was under enemy air attack.” The U.S. Navy requested that the Philippine Clipper return to Wake and she arrived at 07:14 and her cargo, including tires for the American Volunteer Group (the Flying Tigers), were unloaded and she refueled for her return to the Midway Islands. The Naval commanding officer on Wake asked the captain of the Philippine Clipper to carry out a scouting mission while en route and assigned two Marine Grumman F4F-3 Wildcat fighters as escorts. Takeoff was scheduled for 13:00 Wake time.
At about 11:55 Wake time, 34 Japanese bombers attacked the atoll while flying at 1,500 feet (457 meters). Pan Am targets bombed were the PAAVille hotel, a stock room, fuel tanks and many other building, and a radio transmitter. Nine Pan Am employees were killed and two of the Philippine Clipper’s crew were wounded. Luckily, the aircraft, which had been emptied of cargo and people but had a full load of fuel, rode at her moorings. A bomb had splashed 100 feet (30 meters) ahead of the aircraft and she had received 23 bullet holes from the strafing Japanese aircraft, none of which hit the fuel tanks. The aircraft was stripped of all superfluous equipment and all of the passengers and the Caucasian Pan Am employees, less one, boarded her and the plane took off at 13:30 Wake time for Midway.
In September 1942, the two surviving M-130s were impressed for war service as US Navy transports; they were assigned Bureau Numbers (BuNos) but were not assigned a Naval designation. They flew from San Francisco to Honolulu carrying cargo and personnel manned by a Pan Am crew.
On 21 January 1943, the Philippine Clipper as Flight 1104 crashed into a mountain near Boonville, California at 07:30 local about 96 miles (154 kilometers) north-northwest of San Francisco. All 19 people aboard, nine crew and ten passengers, were instantly killed when the aircraft slammed into a small peak at the 2,500 foot (762 meter) level in a thick fog. The aircraft had departed Pearl Harbor at 17:30 the night before, and expected to reach San Francisco at approximately 10:18.
The ten man Pan Am crew consisted of four pilots, three engineers, two radio operators, and a steward. The ten passengers were all U.S. naval officers. Among them was Rear Admiral Robert H. English, the Commanding Officer of the Submarine Force, Pacific Fleet. Rear Admiral English planned to visit submarine support facilities at the Mare Island Naval Shipyard bordering San Pablo Bay, and was accompanied by three of his senior staff officers. Another passenger was Lieutenant Edna Morrow, a Navy nurse diagnosed with terminal cancer who was on her way home to die. Also on board was Captain Robert Holmes Smith, formerly in command of the submarine tender USS Sperry (AS-12), and recently promoted to Commander of Squadron 2, Pacific Submarine Fleet.
Up until the crash, the flight was routine, as evidenced by radio transmissions during the night. A strong tailwind put the flight three and a half hours ahead of schedule. The aircraft ran into poor weather conditions as it flew north over California towards San Francisco. Heavy rain, strong winds, thick cloud cover and fog forced the captain to descend to a lower altitude. At 07:30, the far off-course aircraft crashed into a mountain descending at an angle of 10 degrees, whereupon it clipped a number of trees before crashing, breaking up, and burning. Over a week passed before the wreckage was located, and after it was found the area was cordoned off by soldiers to protect any surviving highly classified military documents that may have been carried aboard.
The Civil Aeronautics Board (CAB) investigated the crash and ultimately determined that the probable cause of the accident was, "Failure of the captain to determine his position accurately before descending to a dangerously low altitude under extremely poor weather conditions during the hours of darkness."
The China Clipper labored on until 13 October 1943, when it was returned to Pan Am after having made 88 trips to Hawaii and back in a year's time. Based in Miami, Florida, it once again began flying passengers and mail from Miami to South America and the Belgian Congo. Uranium ore for the Manhattan Project was one of the clipper's most important "passengers."
Naval ship traffic became so heavy in San Francisco Bay that in 1944, Pan Am moved its operations to San Francisco Municipal Airport. Treasure Island remained an Naval Auxiliary Air Facility as Pan Am continued to use the facility for seaplane overhaul.
China Clipper Flight 161 departed Miami, Florida, at 06:08 for a flight to Leopoldville, Belgian Congo. The flying boat landed at San Juan Harbor, Puerto Rico, at approximately 14:23. After refueling, Flight 161 took off from San Juan, at 16:05 on a contact flight clearance for Port of Spain, Trinidad and Tobago. On board were six crewmen and 24 passengers. Crossing the north coast of Trinidad at an altitude of 4,000 feet (1,219 meters), a gradual let-down was started. The wind was calm, and lights to mark the landing area on the surface of the water were laid out on a 70 degree course. The approach was flown by a captain acting as first officer in the left hand seat. During the first approach he came in too high so he was forced to circle the landing area. During the second try at 21:16, the aircraft descended too low and contacted the water at more than normal landing speed and in a nose-low attitude at a point 1.25 miles (2.01 kilometers) short of the intended landing area. As the plane came to an abrupt stop in the water, the hull broke in two at a point about 3 feet (91 centimeters) aft of the hull step and the rear part of the hull was forced up and forward. Water poured into the cabin and major portion of the flying boat sank immediately. Twenty three of the 30 passengers and crew died. The probable cause found by the investigating board was, "(1) First Officer failure to realize his proximity to the water and to correct his attitude for a normal landing and, (2) the lack of adequate supervision by the Captain during the landing, resulting in the inadvertent flight into the water in excess of normal landing speed and in a nose-down attitude."
Survivors On Display In The U.S.
None. All three aircraft destroyed.
48230: Philippine Clipper
48231: China Clipper
Wingspan: 130 feet (39.62 meters)
Length: 90 feet 10.5 inches (27.70 meters)
Height: 24 feet 7 inches (7.49 meters)
Empty Weight: 25,363 pounds (11,504 kilograms)
Maximum Speed: 180 mph (289.68 km/h)
Service ceiling: 17,000 feet (5,181.60 meters)
With 12 passengers: 3,200 miles (5,149.90 kilometers)
With mail: 4,000 miles (6,436.38 kilometers)