Tag Archives: Aircraft Accident

5 April 1950

Martin JRM-3 Mars Bu. No. 76822, Marshall Mars, burning off Diamond Head, Oahu, Hawaiian Islands, 5 April 1950. (U.S. Navy)
Martin JRM-3 Mars Bu. No. 76822, Marshall Mars, burning off Diamond Head, Oahu, Hawaiian Islands, 5 April 1950. (U.S. Navy)

While on a test flight following an engine change, a United States Navy Martin JRM-3 Mars seaplane, Marshall Mars, Bu. No. 76822, suffered an engine fire (inboard, left wing) and made an emergency landing at Ke’ehi Lagoon, off Diamond Head, Hawaii, 5 April 1950. The airplane’s crew was rescued but the airplane exploded and sank.

The wreck was discovered on the sea floor in August 2004 at a depth of approximately 1,400 feet (427 meters).

The Martin JRM Mars was a large four-engine flying boat transport built by the Glenn L. Martin Company for the U. S. Navy. originally designed as a patrol bomber, the prototype XPB2M-1 Mars made its first flight on 3 July 1942, Only five transport variants were built, four designated JRM-1, with the last one being a JRM-2. Each airplane was given an individual name derived from the names of island chains in the Pacific Ocean: Marianas MarsHawaii MarsPhilippine MarsMarshall Mars and Caroline Mars. These airplanes were used to transport personnel and cargo between the West Coast of the United States and the Hawaiian Islands. All were upgraded to JRM-3.

Four Martin JRM-3 Mars flying boats in formation. (U.S. Navy)
Four Martin JRM-3 Mars flying boats in formation. (U.S. Navy)

The Martin JRM-2 Mars had a normal crew of 4, with accommodations for a relief crew. It was designed to carry 138 combat troops or 34,000 pounds (15,422 kilograms) of cargo. It was 120 feet, 3 inches (36.652 meters) long with a wingspan of 200 feet, 0 inches (60.960 meters) and height of 43 feet, 8 inches (13.310 meters), with beaching gear. The wing area was 3,686 square feet (342.4 square meters). The flying boat had an empty weight of 80,701 pounds (36,605 kilograms) and a maximum takeoff weight (MTOW) 0f 165,000 pounds (74,843 kilograms).

Martin JRM-2 Mars three-view illustration with dimensions. (U.S. Navy)

A NASA publication states, “A zero-lift drag coefficient of 0.0233 and a maximum lift-drag ratio of 16.4 made the JRM the most aerodynamically efficient of any of the flying boats. . . .”

Martin JRM-3 Mars, Bu.No. 76822, Marshall Mars. (U.S. Navy)
Martin JRM-3 Mars, Bu.No. 76822, Marshall Mars. (U.S. Navy)

The Martin Mars was powered by four air-cooled, supercharged, direct-fuel-injected, 3,347.662-cubic-inch-displacement (54.858 liter) Wright Aeronautical Division R-3350-24WA (Cyclone 18 825C18BD1) (also known as the Duplex-Cyclone), a two-row 18-cylinder radial engines with a compression ratio of 6.70:1 and water/alcohol injection. This engine has a normal power rating of 2,000 horsepower at 2,400 r.p.m at 5,500 feet (1,676 meters) and 1,800 horsepower at 2,400 r.p.m. at 15,000 feet (4,572 meters). The engine’s takeoff power rating is 2,500 horsepower at 2,900 r.p.m. 100/130 octane aviation gasoline was required. The engines drove four-bladed 16 foot, 8 inch (5.080 meter) Curtiss Electric variable-pitch propellers through a 0.4375:1 gear reduction. (After modification to the JRM-3, the propellers on the inboard engines were reversible.) The R-3350-24WA is 6 feet, 8.58 inches (2.047 meters) long, and 4 feet, 6.13 inches (1.375 meters) in diameter. Its dry weight is 2,822 pounds (1,280 kilograms).

The JRM-3 had a cruise speed of 165 knots (190 miles per hour/306 kilometers per hour) and a maximum speed of 211 knots (243 miles per hour/391 kilometers per hour) at 15,600 feet (4,755 meters). The service ceiling was 19,700 feet (6,005 meters) and its range was 3,790 nautical miles (4,361 statute miles/7,019 kilometers).

A U.S. Navy Martin JRM Mars. (Glenn L. Martin Co.)
A U.S. Navy Martin JRM Mars. (Glenn L. Martin Co.)

© 2019, Bryan R. Swopes

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4 April 1975

Lockheed C-5A Galaxy 68-0218 lifts off from Tan Son Nhut Air Base, South Vietnam, 4 April 1975. (CORBIS)
Lockheed C-5A Galaxy 68-0218 lifts off from Tan Son Nhut Air Base, South Vietnam, 4:00 p.m., Friday, 4 April 1975. (CORBIS)

4 April 1975: Operation Babylift. As the end of the Vietnam War approached, it was decided to evacuate 2,000 orphans, most in the care of an American hospital in Saigon, Republic of South Vietnam, and to take them to safety within the United States. The first flight was aboard a U.S. Air Force Lockheed C-5A Galaxy heavy lift transport, serial number 68-0218, piloted by Captains Dennis W. Traynor III and Tilford Harp.

A medical team from Clark Air Base, The Philippines, commanded by First Lieutenant Regina Claire Aune, Nurse Corps, United States Air Force, was aboard when the huge transport plane landed at Tan Son Nhut Air Base in Saigon. When it was discovered that there would be about 250 orphans aboard, many of them sick or injured, another medical team from a C-141 Starlifter volunteered to accompany Lieutenant Aune’s team for the outbound flight.

When the Galaxy took off from Saigon at 4:00 p.m., there were 328 people aboard, including flight crew, medical teams, orphans and their escorts, as well as other U.S. personnel.

The C-5A quickly climbed to 23,000 feet (7,010 meters). Just a few minutes after takeoff, the locks of the rear loading ramp failed. Explosive decompression hurled people and equipment throughout the airplane which instantly filled with fog. Lieutenant Aune was thrown the entire length of the upper deck. The airplane was severely damaged with two hydraulic systems inoperative and many flight control cables severed.

The pilots could only control the airplane with engine thrust. They began an emergency descent and turned back to Tan Son Nhut.

Helicopters standing by near the wreck of the Lockheed C-5A Galaxy. (NPR)

Unable to maintain flight, at about 4:45 p.m., the Galaxy touched down in a rice paddy two miles short of the runway at 270 knots (500 kilometers per hour). It slid for a quarter mile, became airborne for another half mile, then touched down and slid until it hit a raised dike and broke into four sections. 138 people were killed in the crash.

Wreckage of the Lockheed C-5A Galaxy transport. (NPR)
Colonel Regina C. Aune, USAF NC (U.S. Air Force)
Colonel Regina Claire Aune, NC USAF (U.S. Air Force)

Although herself seriously injured, Lieutenant Aune began evacuating the children. When rescue helicopters arrived, they were unable to land close to the wrecked transport, so the children had to be carried.

After she had helped to carry about eighty babies, Regina Aune was unable to continue. She asked the first officer she saw to be relieved of her duties and then passed out. At a hospital it was found that she had a broken foot, broken leg and broken vertebra in her back, as well as numerous other injuries.

Cheney Award (U.S. Air Force)

Regina Aune became the first woman to be awarded the Cheney Award by the Air Force, which was established in 1927 and is awarded “to an airman for an act of valor, extreme fortitude or self-sacrifice in a humanitarian interest, performed in connection with aircraft, but not necessarily of a military nature.

11 members of the crew of the Galaxy were among the dead, including Captain Mary Therese Klinker, Nurse Corps, United States Air Force.

Captain Mary T. Klinker, NC USAF. (St. Elizabeth’s School of Nursing)

Mary Therese Klinker was born at Lafayette, Indiana, 3 October 1947. She was the daughter of Paul Edward Klinker and Thelma Mary Deane Klinker. She attended Central Catholic High School in Lafayette, graduating in 1965. She then enrolled at St. Elizabeth’s School of Nursing, also in Lafayette. She graduated as a Registered Nurse, May 1968. On graduation, Miss Klinker worked for St. Elizabeth’s.

Miss Klinker joined the United States Air Force, 9 January 1970, and was commissioned as a lieutenant in the Nurse Corps. She qualified as a flight nurse and was promoted to the rank of captain. In 1974, Captain Klinker was assigned to the 10th Aeromedical Evacuation Squadron, Travis Air Force Base, Fairfield, California.

Airman’s Medal

Captain Mary Therese Klinker, Nurse Corps, United States Air Force, 10th Aeromedical Evacuation Squadron, was the last United States service woman to die in the Vietnam War. Captain Klinker was posthumously awarded the Airman’s Medal and the Meritorious Service Medal. She is buried at St. Boniface Cemetery in her home town of Lafayette, Indiana.

The pilots, Captain Dennis W. Traynor III and Captain Tilford W. Harp, were both awarded the Air Force Cross for what General Paul Carlton, Commander, Military Airlift Command, called “one of the greatest displays of airmanship I have ever heard related.”

Capt. Bud Traynor was piloting the C-5A Galaxy that crashed in 1975 in Saigon as part of Operation Babylif
Captain Dennis W. Traynor III, United States Air Force



Action Date: 3-Apr-75

Service: Air Force

Rank: Captain

Company: 22d Airlift Squadron

Division: Clark Air Base, Philippine Islands

Air Force Cross
Air Force Cross

The President of the United States of America, authorized by Title 10, Section 8742, United States Code, takes pleasure in presenting the Air Force Cross to Captain Dennis W. Traynor, III, United States Air Force, for extraordinary heroism and airmanship while engaged in a humanitarian mission as Aircraft Commander of an Air Force C-5A aircraft of the 22d Airlift Squadron, Clark Air Base, Philippine Islands, in action at Saigon, Vietnam on 3 April 1975. On that date, the aircraft, carrying 330 passengers and crew, experienced a serious in-flight emergency which could have resulted in the loss of life for all aboard. With no aircraft controls except one aileron and the engines, Captain Traynor guided the crippled aircraft to a crash landing in a rice paddy, thereby saving the lives of 176 of the people on board. Through his extraordinary heroism, superb airmanship, and aggressiveness, Captain Traynor reflected the highest credit upon himself and the United States Air Force.



Action Date: 3-Apr-75

Service: Air Force

Rank: Captain

Company: 22d Airlift Squadron

Division: Clark Air Base, Philippine Islands

Air Force Cross
Air Force Cross

The President of the United States of America, authorized by Title 10, Section 8742, United States Code, takes pleasure in presenting the Air Force Cross to Captain Tilford W. Harp, United States Air Force, for extraordinary heroism and airmanship while engaged in a humanitarian mission as Co-Pilot of an Air Force C-5A aircraft of the 22d Airlift Squadron, Clark Air Base, Philippine Islands, in action at Saigon, Vietnam, on 3 April 1975. On that date, his aircraft, carrying 330 passengers and crew, experienced a serious in-flight emergency which could have resulted in the loss of life for all aboard. With no aircraft controls except one aileron and the engines, Captain Harp provided exceptionally vital assistance to the Aircraft Commander in guiding the crippled aircraft to a crash landing in a rice paddy, thereby saving the lives of 176 of the people on board. Through his extraordinary heroism, superb airmanship, and aggressiveness, Captain Harp reflected the highest credit upon himself and the United States Air Force.

Crash site of Operation Babylift's Lockheed C-5A Galaxy, 68-0218, near Tan Son Nhut Air Base, South Vietnam, 4 April 1975. (U.S. Air Force)
Crash site of Operation Babylift’s Lockheed C-5A Galaxy, 68-0218, near Tan Son Nhut Air Base, South Vietnam, 4 April 1975. (U.S. Air Force)

© 2019, Bryan R. Swopes

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3 April 1946

Bell Model 47, s/n 1, NX41962. This helicopter would be re-registered NC1H. (Niagara Aerospace Museum)

3 April 1946: The first commercially certified helicopter, Bell Model 47 NC1H, serial number 1, was being flown by two Bell Aircraft Corporation test pilots, Edward F. Hensley and Gerald Arthur (“Jay”) Demming. Hensley was teaching Demming to fly the aircraft.

Demming was hovering the helicopter about 15 feet (4½ meters) above the ground and began to transition to forward flight. Checking the instruments, he noticed that the engine was turning 3,100 r.p.m., the upper limit of its operating range. Intending to reduce the r.p.m., he moved the collective pitch control lever.

When the collective pitch lever is raised (controlled by the helicopter pilot’s left hand), it causes the angle of attack of all main rotor blades to increase, “collectively.” While this increases the amount of lift being produced, it also increases drag, which slows the rotation of both the main rotor and engine. Lowering the collective lever has the opposite effect. Drag is reduced, and the rotor and engine accelerate.

In an early helicopter like the Model 47, the pilot must manually correlate engine r.p.m. with main rotor collective pitch and tail rotor collective pitch. A twist-grip throttle is on the forward end of the collective lever for this purpose. Throttle adjustments are continuous during helicopter flight, as any change in the other controls will effect engine speed.

Bell test pilot Edward F. Hensley at the controls of an early version of the Bell 47. Hensley’s right hand is on the “cyclic.” This photograph provides a good view of the the helicopter’s flight control system. The three vertical rods behind the pilot control the stationary swash plate, which is mounted at the top of the cylindrical transmission. The center rod controls collective pitch, and the outer two, cyclic pitch. Above the rotating swash plate, two angled pitch control rods (on either side of the main rotor mast) lead to the stabilizer bar. Smaller rods continue to two hydraulic dampers, and then to the pitch horns on the main rotor blade grips. (Niagara Aerospace Museum)
Dual tachometer from a Bell 47G-3B1. Engine r.p.m. is indicated on the outer scale, while rotor r.p.m. is shown on the inner scale.

As Demming was new to the helicopter, he had not yet learned to make these power adjustments automatically. Rather than raise the collective to slow the engine r.p.m., he inadvertently lowered it. This caused a sudden decrease in the rotor blades’ angle of attack and a corresponding decrease in drag. The load on the engine was decreased, but the throttle setting was not reduced accordingly. The engine accelerated to 3,400 r.p.m., which would have driven the main rotor to 378 r.p.m., 5% beyond its maximum operating r.p.m. (“red line”).

Recognizing his error, Demming raised the collective to control the engine/rotor r.p.m.

There was a violent shock. NC1H fell to the ground from a height Demming estimated at 30–50 feet (9–15 meters).

The wreck of the first civil-certified helicopter, Bell Model 47, serial number 1, NC1H, at Niagara Falls Airport, 3 April 1946. The main rotor blades are not seen in this photograph.(Niagara Aerospace Museum)

After the impact, both Demming and Hensley were unconscious. Demming soon regained consciousness and got out of the cockpit, while airport fire/rescue personnel looked after Hensley.

Hensley had fractured three vertebra and was initially not expected to survive his injuries, but he did eventually recover.

NC1H, the first civil-certified helicopter, was damaged beyond repair.

NC1H (Niagara Aerospace Museum)

In photographs of the damaged helicopter, the main rotor yoke, blade grips, pitch horns, drag braces and the main rotor blades are nowhere to be seen. The gimbal ring, static stop, main rotor retaining nut and stabilizer bar are still in place. This suggests that the hub failed and the associated parts were thrown outward, away from the axis of rotation.

With nothing to support it in flight, the rest of the helicopter dropped to the ground like a stone from your hand.

NC1H (originally registered NX41962) had first flown on 8 December 1945, and had received the very first civil helicopter Type Certificate, H-1, on 8 March 1946.

At the time of the accident, NC1H had 75 hours, 42 minutes, total time (TTAF). Its engine had accumulated 136 hours, 50 minutes, since being manufactured (TTSN).

After the crash, NC1H’s registration number was reassigned to s/n 11.

NC1H (Niagara Aerospace Museum)

The Bell 47 series was constructed of a welded tubular steel airframe with a sheet metal cockpit and a characteristic plexiglas bubble canopy. In the original configuration, it had a four-point wheeled landing gear, but this was soon replaced with a tubular skid arrangement. It was a two-place aircraft with dual flight controls.

The first Bell Model 47 had an overall length (with rotors turning) of 39 feet, 7½ inches (12.078 meters). The main rotor diameter was 33 feet, 7 inches (10.236 meters). The length of the fuselage, from the front of the canopy to the trailing edge of the tail rotor disc, was 29 feet, 3½ inches (8.928 meters). The helicopter’s height, to the top of the main rotor mast, was 9 feet, 2–7/16 inches (2.805 meters).

NC1H had an empty weight of 1,393 pounds (632 kilograms). Its gross weight was 2,100 pounds (953 kilograms).

The Bell 47’s main rotor is a two-bladed, under-slung, semi-rigid assembly that would be a characteristic of helicopters built by Bell for decades. The blades were constructed of laminated wood. A stabilizer bar was placed below the hub and linked to the flight controls through hydraulic dampers. This made for a very stable aircraft. The main rotor turns counter-clockwise, as seen from above. (The advancing blade is on the right.) Its normal operating range is 322–360 r.p.m. (294–360 r.p.m. in autorotation).

The tail rotor is positioned on the right side of the tail boom in a tractor configuration. It has a diameter of 5 feet, 5 inches (1.676 meters) and rotates counter-clockwise as seen from the helicopter’s left. (The advancing blade is above the axis of rotation.) The tail rotor blades were also made of wood.

Power was supplied by an air-cooled, normally-aspirated, 333.991-cubic-inch-displacement (5.473 liter) Franklin Engine Company 6V4-178-B3 vertically-opposed six cylinder engine, serial number 17008, which was rated at 178 horsepower at 3,000 r.p.m. Engine torque was sent through a centrifugal clutch to a transmission. The mast (the main rotor drive shaft) was driven through a two-stage planetary gear reduction system with a ratio of 9:1. The transmission also drove the tail rotor drive shaft, and through a vee-belt/pulley system, a large fan to provide cooling air for the engine.

The new helicopter had a cruise speed of 75 miles per hour (121 kilometers per hour) and a maximum speed (VNE) of 80 miles per hour (129 kilometers per hour). NC1H had a service ceiling of 11,400 feet (3,475 meters).

The Bell 47 was produced at the plant in New York, and later at Fort Worth, Texas. It was steadily improved and remained in production until 1974. In military service the Model 47 was designated H-13 Sioux, (Army and Air Force), HTL (Navy) and HUG (Coast Guard). The helicopter was also built under license by Agusta, Kawasaki and Westland. More than 7,000 were built worldwide and it is believed that about 10% of those remain in service.

In 2010, the type certificates for all Bell 47 models was transferred to Scott’s Helicopter Service, Le Sueur, Minnesota, which continues to manufacture parts and complete helicopters.

Gerald A. (“Jay”) Demming, Bell Aircraft Corporation test pilot. (Niagara Aerospace Museum)

Gerald Arthur (“Jay”) Demming was born 4 July 1918 at Niagara Falls, New York. He was the son of Arthur L. Demming, Jr., a factory foreman, and Marie I. Demming. He attended La Salle High School, graduating in 1936, then the University of Illinois at Urbana Champaign.

While at college, Demming entered the Civilian Pilot Training Program. He became a multi-engine and instrument flight instructor at Dominion Skyways Ltd., a flight school at Malton, Ontario, Canada. He was next employed as a civilian pilot for the Royal Canadian Air Force.

On 30 May 1942, Jay Demming married Miss Audrey Mary Prowse. They would have two children. They divorced im May 1966 in Brevard County, Florida.

Gerald Arthur Demming died 20 May 1996, at Plant City, Hillsborough, Florida.

Edward Freeland Hensley, Bell Aircraft Corporation test pilot. (LeslieGift)

Edward Freeland Hensley was born 22 November 1910 at Mountain Park, Oklahoma. He was the first of three children of Edward Hensley, owner of a real estate company, and Mamie A. Freeland Hensley.  He attended John Brown College at Siloam Springs, Arkansas.

Hensley had brown hair and blue eyes. He was 5 feet, 8 inches tall and weighed 135 pounds.

Hensley married Miss Edith Hyla Collins in Oklahoma City, Oklahoma, 15 August 1931. They would have four children.

In teh mid-1930s, Hensley worked for the U.S. Postal Service in Oklahoma City. He was a specical dleiveries manager.

Hensley was issued a commercial pilot’s license in 1938. By 1940, he was a flight instructor at McConnell Flying Service, Parsons, Kansas. He was next employed as a civilian flight instructor for Brayton Flying Services, inc., at the U.S. Army contract flight school in Cuero Municipal Airport, Cuero, Texas. He then joined Bell Aircraft Corporation as a test pilot.

He later was a test pilot for the Boeing B-47 Stratojet at Wichita, Kansas.

Edward Freeland Hensley died in June 1969 in Wichita.

© 2019, Bryan R. Swopes

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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

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27 March 1977

A recent photograph looking west-northwest (300° Magnetic) along Runway 30 at Los Rodeos Airport (TFN), Tenerife, Canary Islands. (© Claudio)

27 March 1977: The deadliest accident in the history of aviation occurred when two Boeing 747 airliners collided on the runway on the island of Tenerife in the Canary Islands. 583 people died.

A terrorist incident at Gran Canaria International Airport (LPA) on the island of Gran Canaria resulted in the airport being closed for flight operations. This forced many trans-Atlantic airliners to divert to the smaller Los Rodeos Airport (TFN) on Tenerife. The ramp and taxiways at Los Rodeos were congested and refuelers were overwhelmed by the increased traffic, which led to many delays.

A Pan American World Airways Boeing 747-121, N750PA, similar to N736PA. (Michael Gilliand via Wikipedia)

Los Rodeos Airport has only one runway, Runway 12/30, with a parallel taxiway and four short taxiways joining the two.

Pan American World Airways’ Flight 1736, a Boeing 747-121, FAA registration number N736PA, named Clipper Victor ¹ was ready for takeoff with 380 passengers and crew, but had to “back taxi” on Runway 12 (“One-Two”) because the parallel taxiway was jammed with airplanes. The airliner proceeded east-southeast, intending to exit the runway to the parallel taxiway after passing by the congestion around the terminal.

Also on the runway was Koninklijke Luchtvaart Maatschappij (KLM) Flight 4805, a Boeing 747-206B, PH-BUF, named Rijn (“Rhine”). The KLM jumbo jet had 248 passengers and crew members on board. Flight 4805 had back-taxied for the entire length of Runway 12, then made a 180° turn to align itself with Runway 30, the “active” runway.

KLM Royal Dutch Airways’ Boeing 747-206B PH-BUF, Rijn. (clipperarctic via Wikipedia)

Weather at the time of the accident was IFR, with low clouds and fog. Visibility on the runway was restricted to about 1,000 feet (305 meters). Takeoff rules required a minimum of 2,300 feet (701 meters). What happened next was a misunderstanding between the air traffic controllers and the crew of both airliners.

The control tower instructed KLM 4805 to taxi into position on Runway 30 (“Three-Zero”) for takeoff, and to hold there for release. The Pan Am airliner was told to taxi off the runway and to report when clear. The tower controllers could not see either airliner because of the fog, and their flight crews could not see each other.

The aircraft commander of the Dutch airliner, that company’s Chief Pilot and Chief Flight Instructor, Captain Jacob Veldhuyzen Van Zanten, apparently misunderstood what was occurring and radioed to the tower that he was taking off. He then accelerated.

The crew in the Pan Am airliner heard the KLM pilot report that he was taking off, immediately turned left and ran the engines up to full throttle in order to try to get off the runway. With the KLM 747 accelerating through the fog, its flight crew belatedly realized that the other airliner was still ahead of them. Too late to stop, they applied full power and pulled the nose up trying to takeoff. The tail of their airplane actually dragged over sixty feet (18 meters) on the runway because its extreme nose up angle.

Computer-generated illustration of the moment of impact as KLM Flight 4805 hits Pan Am Flight 1736 on the runway at Tenerife. (PBS Nova)

KLM 4805 lifted off about 300 feet (91 meters) from Pan Am 1736, and because of the high angle of attack, its nose wheel actually passed over American airliner’s fuselage, but the rest of the Dutch airplane hit at 140 knots (259 kilometers per hour). Clipper Victor was ripped in half, caught fire and exploded. Rijn crashed about 250 yards (229 meters) down the runway, and it also caught fire and exploded.

All 248 people aboard the Royal Dutch Airlines airplane were killed. Miraculously, there were 61 survivors from the Pan Am Clipper, including the co-pilot, but the remaining 335 died.

Two Boeing 747 airliners collided on the runway at Tenerife, 27 March 1977. (Unattributed)

The 747-100 series was the first version of the Boeing 747 to be built. It was operated by a flight crew of three and was designed to carry 366 to 452 passengers. It is 231 feet, 10.2 inches (70.668 meters) long with a wingspan of 195 feet, 8 inches (59.639 meters) and overall height of 63 feet, 5 inches (19.329 meters). The interior cabin width is 20 feet (6.096 meters), giving it the name “wide body.” Its empty weight is 370,816 pounds (168,199 kilograms) and the Maximum Takeoff Weight (MTOW) is 735,000 pounds (333,390 kilograms).

The 747-100 is powered by four Pratt & Whitney JT9D-7A high-bypass ratio turbofan engines. The JT9D is a two-spool, axial-flow turbofan engine with a single-stage fan section, 14-stage compressor (11 high- and 3 low-pressure stages) and 6-stage turbine (2 high- and 4 low-pressure stages). The engine is rated at 46,950 pounds of thrust (208.844 kilonewtons), or 48,570 pounds (216.050 kilonewtons) with water injection (2½-minute limit). This engine has a maximum diameter of 7 feet, 11.6 inches (2.428 meters), is 12 feet, 10.2 inches (3.917 meters) long and weighs 8,850 pounds (4,014 kilograms).

The 747-100 has a cruise speed of 0.84 Mach (555 miles per hour, 893 kilometers per hour) at 35,000 feet (10,668 meters). The maximum certificated operating speed is 0.92 Mach. The airliner’s maximum range is 6,100 miles (9,817 kilometers).

The Boeing 747 has been in production for 48 years. More than 1,520 have been delivered to date. 205 of these were the 747-100 series. The U.S. Air Force has selected the Boeing 747-8 as the next presidential transport aircraft.

¹ Pan American World Airways’ Boeing 747 Clipper Victor was the very first Boeing 747 in service. It made its first commercial passenger flight, New York to London, 22 January 1970. Another airliner, Clipper Young America, was scheduled to  make that flight but suffered mechanical problems shortly before departure. Clipper Victor was substituted, but Pan Am changed the airliner’s name to Clipper Young America. On 2 August 1970, N736PA was hijacked to Cuba, and afterwards, to avoid the negative publicity, the name of the 747 was changed back to Clipper Victor.

© 2019, Bryan R. Swopes

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