Tag Archives: Boeing 377 Stratocruiser

16 October 1956

Boeing 377 Stratocruiser N90943, Pan American World Airways' Sovereign of the Skies, seen over San Francisco, circa 1947. (University of Washington Libraries Digital Collections, TRA0138)
Boeing 377 Stratocruiser N90943, Pan American World Airways’ Sovereign of the Skies, seen over San Francisco, circa 1947. (University of Washington Libraries Digital Collections, TRA0138)

16 October 1956: Pan American World Airways’ Flight 6 was a scheduled around-the-world passenger flight. The final leg, Honolulu to San Francisco, was flown by a Boeing Model 377 Stratocruiser with civil registration N90943, and named Sovereign of the Skies.

The airplane had a flight crew of 7 and carried 24 passengers. The aircraft commander was Captain Richard N. Ogg, a veteran pilot with more than 13,000 flight hours accumulated over twenty years. First Officer George L. Haaker, Flight Engineer Frank Garcia, Jr., and Navigator Richard L. Brown completed the flight crew. The cabin crew were Purser Patricia Reynolds, who had been with Pan Am for over ten years, and Stewardesses Katherine S. Araki and Mary Ellen Daniel.

The flight from Honolulu to San Francisco was estimated to take 8 hours, 54 minutes. Captain Ogg had the airplane fueled for a total flight time of 12 hours, 18 minutes.

Pan American World Airlines’ Boeing 377 Stratocruiser, Clipper America. This airplane is similar to Sovereign of the Skies. (Boeing)

Flight 6 departed Honolulu at 8:24 p.m., Hawaii Standard Time, 15 October (06:24, 16 October, GMT), and climbed to 13,000 feet (3,962 meters) on course.

4 hours, 38 minutes after takeoff, Flight 6 requested a pre-planned climb to 21,000 feet (6,400 meters), at a point about half-way—in terms of flight time—between the departure point and destination, what is dramatically called “The Point of No Return” in suspense movies. (Actually, this is called the Equal Time Point: Taking into consideration forecast winds, the time to fly back to the departing point is the same as the time to continue toward the destination.)

On leveling at the new cruise altitude at 1:19 a.m. (HST), First Officer Haaker reduced engine power. The propeller for the Number 1 engine, the outside engine on the left wing, suffered a prop governor failure and began to overspeed, with engine r.p.m. actually exceeding the limits of its tachometer. This created a very dangerous condition: If the propeller turned fast enough, it could be torn apart by centrifugal force. (See This Day In Aviation, 22 March 1956, for an example.)

The crew was unable to feather the propeller, which would cause its four blades to turn parallel to the slip stream, and increasing the load on the engine while reducing aerodynamic drag. The engine and propeller continued to turn at dangerously high speed so Captain Ogg decided to force the engine to stop by cutting off its lubricating oil supply. This caused the engine to seize but the propeller continued to “windmill.”

The drag caused by the propeller slowed the airplane considerably and the three remaining engines had to run at high power for the Boeing 377 to maintain its altitude. The Number 4 engine (the outer engine on the right wing) was developing only partial power at full throttle. At 2:45 a.m., it began to backfire and had to be shut down.

The airplane began to descend toward the ocean’s surface.

With the drag of the windmilling Number 1 propeller and only two engines running, Sovereign of the Skies could fly at just 140 knots (161 miles per hour/259 kilometers per hour), not fast enough to reach San Francisco or to return to Honolulu before running out of fuel. The navigator estimated that they would run out of fuel 250 miles (402 kilometers) from land.

The United States Coast Guard kept a high endurance cutter on station between Hawaii and California, at a point known as Ocean Station November. This ship provided assistance with weather information, radio communications and was available to assist should an emergency arise aboard trans-Pacific airplanes.

USCGC Pontchartrain (WHEC 70) circa 1958. (U.S. Coast Guard)
USCGC Pontchartrain (WHEC 70) circa 1958. (U.S. Coast Guard)

On 16 October 1956, this cutter was USCGC Pontchartrain (WHEC 70), under the command of Commander William K. Earle, USCG. Pontchartrain was a 255-foot (77.7 meter) Lake-class patrol gunboat built by the U.S. Coast Guard ship yard at Curtiss Bay, Maryland, and commissioned 28 July 1945. The ship was redesignated as a high endurance cutter in 1948. Pontchartrain had a complement of 143 men.

The ship was 254 feet (77.42 meters) long, overall, with a beam of 43 feet, 1 inch (13.13 meters) and draft of 17 feet, 3 inches (5.25 meters). Its full load displacement was 1,978 tons (1,794 Metric tons). It was powered by a Westinghouse turbo-electric drive of 4,000 shaft horsepower and was capable on making 17.5 knots (20.41 miles per hour, or 32.41 kilometers per hour). Its maximum range was 10,376 miles (19,216 kilometers).

Pontchartrain was armed with a single 5-inch/38-caliber naval gun forward. It carried Hedgehog anti-submarine mortars and Mk 23 acoustic-homing antisubmarine torpedoes.

Captain Ogg notified Ponchartrain that he intended to ditch the airliner near the ship. The Coast Guard provided Captain Ogg with wind and wave information—five-foot (1.5 meter) swells, wind at eight knots (4 meters per second) from the northwest—and advised the best heading for ditching. The ship laid a trail of foam to mark this course.

Pan American World Airways Flight 6, a Boeing 377 Stratocruiser, ditches in the North Pacific Ocean near USCGC Pontchartrain (WHEC 70), 6:15 am., 16 October 1956. (U.S. Coast Guard)
Pan American World Airways Flight 6, a Boeing 377 Stratocruiser, ditches in the North Pacific Ocean near USCGC Pontchartrain (WHEC 70), 6:15 am., 16 October 1956. (U.S. Coast Guard)

At 6:15 a.m., at approximately 90 knots airspeed (104 miles per hour/167 kilometers per hour), the Boeing 377 landed on the water. A wing hit a swell, spinning the airplane to the left. The tail broke off and the airplane began to settle.

Pan American World Airways’ Boeing 377 Stratocruiser, Sovereign of the Skies, with its fuselage broken after ditching in the North Pacific Ocean, 16 October 1956. (Pan Am Historical Foundation/The New York Times)

Injuries were minor and all passengers and crew evacuated the airliner. They were immediately picked up by Pontchartrain.

Captain Ogg and Purser Reynolds were the last to leave the airplane.

Twenty minutes after touching down, at 6:35 a.m., Sovereign of the Skies sank beneath the ocean’s surface.

Sovereign of the Seas sinks into the Pacific Ocean, 16 October 1956. (U.S. Coast Guard)
Sovereign of the Skies sinks into the Pacific Ocean, 16 October 1956. (U.S. Coast Guard)

Pan American’s Sovereign of the Skies was a Boeing Model 377-10-29, construction number 15959, originally operated by American Overseas Airlines as Flagship Holland, and later, Flagship Europe. Pan Am acquired the airliner during a merger. On 16 October 1956, the airplane had accumulated 19,820:51 total time on the airframe (TTAF) since it was built.

The Boeing 377 was a large, four-engine civil transport which had been developed, along with the military C-97 Stratofreighter, from the World War II B-29 Superfortress long-range heavy bomber. It utilized the wings and engines of the improved B-50 Superfortress. The airplane was operated by a flight crew of four. It was a double-deck aircraft, with the flight deck, passenger cabin and galley on the upper deck and a lounge and cargo compartments on the lower. The airliner was pressurized, and could maintain Sea Level atmospheric pressure while flying at 15,500 feet (4,724 meters). The Model 377 could be configured to carry up to 100 passengers, or 28 in sleeping births.

The Stratocruiser was 110 feet, 4 inches (33.630 meters) long with a wingspan of 141 feet, 3 inches (43.053 meters) and overall height of 38 feet, 3 inches (11.659 meters). Empty weight was 83,500 pounds (37,875 kilograms) and the maximum takeoff weight was 148,000 pounds (67,132 kilograms). Sovereign of the Skies had a gross weight of 138,903 pounds (63,005 kilograms) when it took off from Honolulu.

Crew members of Pan American World Airways Flight 6 receive commendations for their service during the emergency of 16 October 1956. Left to right, Captain Richard N. Ogg; Navigator Richard L. Brown; Purser Patricia Reynolds; (unidentified); First Officer George L. Haaker; Flight Engineer Frank Garcia, Jr.. (Pan Am Historical Foundation/The New York Times)

The airliner was powered by four air-cooled, supercharged 4,362.49-cubic-inch-displacement (71.489 liter) Pratt & Whitney Wasp Major B6 four-row, 28-cylinder radial engines which had a Normal Power rating of 2,650 horsepower at 2,550 r.p.m., and 2,800 horsepower at 2,550 r.p.m. Maximum Continuous. It produced 3,250 horsepower at 2,700 r.p.m. for takeoff (3,500 horsepower with water injection). The engines drove four-bladed Hamilton-Standard Hydromatic, 24260 constant-speed propellers with a diameter of 17 feet, 0 inches (5.182 meters) through a 0.375:1 gear reduction. The Wasp Major B6 was 8 feet, 0.50 inches (2.451 meters) long, 4 feet, 7.00 inches (1.397 meters) in diameter, and weighed 3,584 pounds (1,626 kilograms).

The 377 had a cruise speed of 301 miles per hour (484 kilometers per hour) and a maximum speed of 375 miles per hour (604 kilometers per hour). During testing by Boeing, a 377 reached 409 miles per hour (658 kilometers per hour). Its service ceiling was 32,000 feet (9,754 meters) and the range was 4,200 miles (6,759 kilometers).

Boeing built 56 Model 377 Stratocruisers, with Pan American as the primary user, and another 888 military C-97 Stratofreighter and KC-97 Stratotankers.

A U.S. Coast Guard film of the incident can be seen at:

© 2018, Bryan R. Swopes

Facebooktwitterredditpinterestlinkedinmailby feather

8 July 1947

First flight, Boeing Model 377 Stratocruiser
First flight, Boeing Model 377 Stratocruiser NX90700, c/n 15922. After the flight test program was completed, this airplane was upgraded to the 377-10-26 standard and placed in service with Pan American World Airways as Clipper Nightingale, N1022V

8 July 1947: First flight, Boeing Model 377-10-19 Stratocruiser, Project Test Pilot John Bernard Fornasero. (Fornasero had been the co-pilot on the first flight of the XC-97 Stratofreighter, nearly three years earlier.)

Flight deck of the Boeing Model 377 Stratocruiser. (Boeing)
Flight deck of the Boeing Model 377 Stratocruiser. (Boeing)

The Model 377 was a large, four-engine civil transport which had been developed, along with the military C-97 Stratofreighter, from the World War II B-29 Superfortress long-range heavy bomber. It utilized the wings and engines of the improved B-50 Superfortress. The airplane was operated by a flight crew of four. It was a double-deck aircraft, with the flight deck, passenger cabin and galley on the upper deck and a lounge and cargo compartments on the lower. The airliner was pressurized, and could maintain Sea Level atmospheric pressure while flying at 15,500 feet (4,724 meters). The Model 377 could be configured to carry up to 100 passengers, or 28 in sleeping births.

Airline stewardesses examine a cutaway model of the Boeing 377 Stratocruiser. (Museum of History & Industry, Seattle)

The Stratocruiser was 110 feet, 4 inches (33.630 meters) long with a wingspan of 141 feet, 3 inches (43.053 meters) and overall height of 38 feet, 3 inches (11.659 meters). The airliner had an empty weight of 83,500 pounds (37,875 kilograms) and its maximum takeoff weight was 148,000 pounds (67,132 kilograms).

Boeing Model 377-10-19 Stratocruiser NX90700. (Boeing)
Boeing Model 377-10-19 Stratocruiser NX90700. (Boeing)

The 377-10-19 prototype was powered by four 4,362.49-cubic-inch-displacement (71.49 liter) air-cooled, supercharged Pratt & Whitney Wasp Major B5 four-row, 28-cylinder radial engines. This engine had a compression ratio of 6.375:1 and required 100/130 aviation gasoline. It had a Normal and Maximum Continuous Power rating of 2,650 horsepower at 2,550 r.p.m., and Take Off Power rating of 3,250 horsepower at 2,700 r.p.m. with water/alcohol injection. The Wasp Major B5 was 4 feet, 6.00 inches in diameter and 8 feet, 0.75 inches long. The engine weighed 3,490 pounds (1,583 kilograms).

The following production Stratocruisers were equipped with Pratt & Whitney Wasp Major B6 engines rated at 3,500 horsepower at 2,700 r.p.m. (with water/alcohol injection) for takeoff, and a Normal Power of 2,650 horsepower at 2,550 r.p.m., at 5,500 feet (1,676 meters). The Maximum Continuous Power rating for the B6 was 2,800 horsepower at 2,550 r.p.m. at 3,500 feet (1,067 meters). The Wasp Major B6 was 4 feet, 7.00 inches (1.397 meters) in diameter and 8 feet, 0.50 inches (2.451 meters) long. It weighed 3,584 pounds (1,626 kilograms), dry.

Pan American World Airways Boeing Model 377 Stratocruiser. (Boeing)
Pan American World Airways’ Boeing Model 377-10-26 Stratocruiser, Clipper Nightingale, N1022V, c/n 15922. (Boeing)

The engines drove four-bladed Hamilton Standard Hydromatic constant-speed propellers with a diameter of 17 feet (5.182 meters) through a 0.375:1 gear reduction. The propeller assembly weighed 761 pounds (345 kilograms).

The 377 had a cruise speed of 301 miles per hour (484 kilometers per hour) and a maximum speed of 375 miles per hour (604 kilometers per hour). During testing by Boeing, a 377 reached 409 miles per hour (658 kilometers per hour). Its service ceiling was 32,000 feet (9,754 meters) and the range was 4,200 miles (6,759 kilometers).

Lower deck passenger lounge of a Boeing 377 Stratoliner. (Boeing)
Lower deck passenger lounge of a Boeing 377 Stratoliner. (Boeing)

Boeing built 56 Model 377 Stratocruisers, with Pan American as the primary user, and another 888 military C-97 Stratofreighter and KC-97 Stratotankers.

Following the flight testing program, NX90700 was brought up to the 377-10-26 standard and placed in service with Pan American World Airways, 24 October 1950. It was named Clipper Nightingale and registered N1022V. The airliner remained in Pan Am service until 1960, when it was sold back to Boeing.

N1022V was next sold to Rutas Aéreas Nacionales, S.A. (RANSA) and converted to a freighter. The new owners named it Carlos. It was re-registered YV-C-ERI. The Stratocruiser was finally retired in 1969 and scrapped.

The prototype Boeing 377 Stratocruiser was sold to RANSA and converted to a freighter. It was named "Carlos" and registered YV-C-ERI.
The prototype Boeing 377 Stratocruiser was sold to RANSA and converted to a freighter. It was named “Carlos” and registered YV-C-ERI.

© 2019, Bryan R. Swopes

Facebooktwitterredditpinterestlinkedinmailby feather

2 April 1956

Northwest Airlines, Inc., Boeing 377 Stratocruiser N74608. (BAAA)

2 April 1956: On Monday morning at 8:10 a.m., Pacific Standard Time, Northwest Airlines Flight 2 took off from Seattle-Tacoma Airport en route to New York City, with intermediate stops at Portland, Oregon, and Chicago, Illinois. The airliner, a Boeing 377 Stratocruiser, N74608, had a crew of six and carried 32 passengers. The flight was under the command of Captain Robert Reeve Heard, with First Officer Gene Paul Johnson and Flight Engineer Carl Vernon Thomsen.

The weather at “SeaTac” was overcast, with a ceiling at 1,200 feet (366 meters) and 10 miles (16 kilometers) visibility. The wind was from the east-northeast at 7 knots (3.6 meters per second).

The Boeing reached the cloud layer at 145 knots (167 miles per hour/269 kilometers per hour). The engines were throttled back from takeoff power and the wing flaps were retracted. The airplane suddenly began to buffet severely, as if it were about to stall. (A passenger later said that the airplane “shook like a wet dog.”) It also rolled to the left and Captain Heard had to use full opposite aileron to maintain control. N74608 began to lose altitude.

Northwest Airlines Boeing 377 Stratocruiser. (Minnesota Historical Society)

Captain Heard suspected a split-flap condition, in which, one of the flaps remained partially or fully extended. Initially considering a return to SeaTac, Heard decided that it would be safer to proceed to McChord Air Force Base. The situation continued to worsen. Captain Heard, fearing control would quickly be lost, decided to ditch the Stratocruiser in Puget Sound.

N74608 hit the surface 4.7 nautical miles (5.4 statute miles/8.7 kilometers) from the end of Seattle’s Runway 20, The water was smooth and the airliner coasted to a stop. It then began to take on water. All passengers and crew were evacuated. Two passengers suffered minor injuries. Once in the water, they used seat cushions for flotation. (Flight 2 was not required to carry rafts or life vests.) The water temperature was 42 °F. (5.6 °C.). After about fifteen minutes, the Stratoliner sank in 430 feet (131 meters) of water.

A Northwest Airlines DC-3 flew over the scene and dropped three life rafts. Two U.S. Air Force Grumman SA-16 Albatross amphibians and a U.S. Coast Guard 83-foot (56.6 meters) patrol boat soon arrived on scene. Most of the passengers and crew were rescued. However, four passengers, probably suffering from hypothermia, had drowned. Flight Service Attendant David Victor Razey was missing. The accident occurred on his 27th birthday.¹

A crane barge lifts Boeing 377 N74608 clear of the water. (Civil Aeronautics Board)

The wreck of N74608 was located on the floor of Puget Sound. It was initially moved to shallow water where divers were able to examine it. Later, the airliner was lifted onto a barge.

The Number 1 engine is missing. (Civil Aeronautics Board)

The Stratoliner’s Number 1 engine (outboard, left wing) was missing and never found. Investigators found that the cowl flaps of the remaining three engines were all fully open. They should have been closed for takeoff.

When the flight crew went through the pre-takeoff check list, in response to the prompt, “Cowl flaps set for takeoff,” the flight engineer responded, “Set for takeoff,” when they were actually open.

At takeoff and climb out speeds, open cowl flaps disrupt the flow of air over the wings. With the wing flaps down, this isn’t noticeable, but when the flaps are retracted, a severe buffeting occurs, as parts of the wing begin to stall.

Investigators found “no failure or malfunction of the aircraft, the power plants, or control systems prior to the ditching.”

Probable Cause:

     The Board determines that the probable cause of the accident was the incorrect analysis of control difficulty which occurred on retraction of the wing flaps as a result of the flight engineer’s failure to close the engine cowl flaps—the analysis having been made under conditions of great urgency and within an extremely short period of time available for decision.

—Civil Aeronautics Board Accident Investigation Report SA-319, File No. 1-0051, 9 November 1956, at Page 8

A Northwest Airlines Boeing 377 Stratocruiser. (Charles M. Daniels Collection, San Diego Air & Space Museum Archives)

Northwest Airlines’ N74608 was one of ten Boeing Model 377-10-30 Stratocruisers ordered by the airline. It was built at Seattle, Washington, in 1949, and assigned the manufacturer’s serial number 15954. N74608 carried Northwest’s fleet number, 708. The 377-10-30 was a variant built specifically for Northwest. It can be identified by the rectangular passenger windows.

At the time of the accident, the airliner had flown a total of 18,489 hours (TTAF).

The Model 377 was a large, four-engine civil transport which had been developed, along with the military C-97 Stratofreighter (Boeing Model 367), from the World War II B-29 Superfortress long-range heavy bomber. It utilized the wings and engines of the improved B-50 Superfortress. The airplane was operated by a flight crew of four. It was a double-deck aircraft, with the flight deck, passenger cabin and galley on the upper deck and a lounge and cargo compartments on the lower. The airliner was pressurized and could maintain Sea Level atmospheric pressure while flying at 15,500 feet (4,724 meters). The Model 377 could be configured to carry up to 100 passengers, or 28 in sleeping births.

The Stratocruiser was 110 feet, 4 inches (33.630 meters) long with a wingspan of 141 feet, 3 inches (43.053 meters) and overall height of 38 feet, 3 inches (11.659 meters). The airliner had an empty weight of 83,500 pounds (37,875 kilograms) and the maximum takeoff weight was 148,000 pounds (67,132 kilograms).

Flight deck of the Boeing Model 377 Stratocruiser. (Boeing)

N74608 was powered by four air-cooled, supercharged, 4,362.49-cubic-inch-displacement (71.488 liter) Pratt & Whitney Wasp Major B6 engines. These were four-row, 28-cylinder, radial engines with a compression ratio of 6.7:1.

The B6 had a Normal Power rating of 2,650 horsepower at 2,550 r.p.m., at 5,500 feet (1,676 meters), and Maximum Continuous Power rating of 2,800 horsepower at 2,550 r.p.m. at 3,500 feet (1,067 meters). The Takeoff Power rating was 3,500 horsepower at 2,700 r.p.m. with water/alcohol injection.

The engines drove four-bladed Hamilton Standard Hydromatic 24260 constant-speed propellers with a diameter of 17 feet (5.182 meters) through a 0.375:1 gear reduction.

The Wasp Major B6 was 4 feet, 7.00 inches (1.397 meters) in diameter and 8 feet, 0.50 inches (2.451 meters) long. It weighed 3,584 pounds (1,626 kilograms), dry. The propeller assembly weighed 761 pounds (345 kilograms).

In this photograph of the Boeing 377 assembly plant, the airplane’s cowl flaps are visible immediately behind the engines. (Boeing)

The 377 had a cruise speed of 301 miles per hour (484 kilometers per hour) and a maximum speed of 375 miles per hour (604 kilometers per hour). During testing by Boeing, a 377 reached 409 miles per hour (658 kilometers per hour). Its service ceiling was 32,000 feet (9,754 meters) and the range was 4,200 miles (6,759 kilometers).

Boeing built 56 Model 377 Stratocruisers, with Pan American as the primary user, and another 888 military C-97 Stratofreighter and KC-97 Stratotankers.

¹ David Victor Razey was born 2 April 1929 at Maerdy, Rhondda Cynon Taf, Wales. He had brown hair, hazel eyes and a medium complexion. He was 5 feet, 5 inches (1.65 meters) tall and weighed 140 pounds (63.5 kilograms). Razey became resident of the United States in 1949, and was naturalized as a U.S. citizen, 2 August 1954.

© 2019, Bryan R. Swopes

Facebooktwitterredditpinterestlinkedinmailby feather