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15 February 1946

Douglas XC-112A Liftmaster 45-873 (U.S. Air Force)
Douglas XC-112A 45-873 (W. T. Larkins Collection/Wikipedia)

15 February 1946: First flight of Douglas XC-112A (s/n 36326) 45-873.

In 1944, the U.S. Army Air Corps had requested a faster, higher-flying variant of the Douglas C-54E Skymaster, with a pressurized cabin. Douglas Aircraft Company developed the XC-112A in response. It was completed 11 February 1946 and made its first flight 4 days later. With the end of World War II, military requirements were scaled back and no orders for the type were placed.

Douglas saw a need for a new post-war civil airliner to compete with the Lockheed L-049 Constellation. Based on the XC-112A, the prototype Douglas DC-6 was built and made its first flight four months later, 29 June 1946.

Prototype Douglas DC-6 civil transport. (Century of Flight)

The Air Force ordered the twenty-sixth production Douglas DC-6 as a presidential transport, designated VC-118, The Independence. Beginning in 1951, the Air Force ordered a variant of the DC-6A as a the C-118A Liftmaster military transport and MC-118A medical transport. The U.S. Navy ordered it as the R6D-1.

The Douglas DC-6 was flown by a pilot, co-pilot, flight engineer and a navigator on longer flights. It was designed to carry between 48 and 68 passengers, depending on variant.

The DC-6 was 100 feet, 7 inches (30.658 meters) long with a wingspan of 117 feet, 6 inches (35.814 meters) and overall height of 28 feet, 5 inches (8.612 meters). The aircraft had an empty weight of 55,567 pounds (25,205 kilograms) and maximum takeoff weight of 97,200 pounds (44,090 kilograms).

The initial production DC-6 was powered by four 2,804.4-cubic-inch-displacement (45.956 liter), air-cooled, supercharged Pratt & Whitney Double Wasp CA15 two-row, 18 cylinder radial engines with a compression ratio of 6.75:1. The CA15 had a Normal Power rating of 1,800 h.p. at 2,600 r.p.m. at 6,000 feet (1,829 meters), 1,600 horsepower at 16,000 feet (4,877 meters), and 2,400 h.p. at 2,800 r.p.m with water injection for take off. The engines drove  three-bladed Hamilton Standard Hydromatic 43E60 constant-speed propellers with a 15 foot, 2 inch (4.623 meter) diameter through a 0.450:1 gear reduction. The Double Wasp CA15 was 6 feet, 4.39 inches (1.940 meters) long, 4 feet, 4.80 inches (1.341 meters) in diameter, and weighed 2,330 pounds (1,057 kilograms).

The Douglas DC-6 had a cruise speed of 311 miles per hour (501 kilometers per hour) and range of 4,584 miles (7,377 kilometers).

XC-112A 45-873 was redesignated YC-112A and was retained by the Air Force before being transferred to the Civil Aeronautics Administration at Oklahoma City, where it was used as a ground trainer. 36326 was sold at auction as surplus equipment, and was purchased by Conner Airlines, Inc. Miami, Florida and received its first civil registration, N6166G, 1 August 1956. The YC-112A was certified in the transport category, 20 August 1956.

Conner Airlines sold 36326 to Compañia Ecuatoriana de Aviación (CEA), an Ecuadorian airline. Registered HC-ADJ, Ecuatoriana operated 36326 for several years.

It was next re-registered N6166G, 1 August 1962, owned by ASA International. A few months later, 1 May 1963, 36326 was registered to Trabajeros Aereos del Sahara SA (TASSA) a Spanish charter company specializing in the support of oil drilling operations in the Sahara, registered EC-AUC.

XC-112A was operated as a DC-6, EC-AUC, by TASSA Air Charter, seen here at London Gatwick, 29 August 1964. (RuthAS)
The XC-112A was operated as EC-AUC by TASSA Air Charter, seen here at London Gatwick, 29 August 1964. (RuthAS)

In 1965, with a private owner, 36326 was once again re-registered N6166G. Just two weeks after that, 1 June 1965, 36326 was registered to TransAir Canada as CF-TAX.

A TransAir DC-6
A TransAir DC-6

Two years later, 13 June 1967, Mercer Airlines bought 36326. This time the airplane was registered N901MA. Mercer was a charter company which also operated a Douglas C-47 and Douglas DC-4.

N901MA at Hollywood-Burbank Airport (Bureau d'Archives des Accidents d'Avion)
N901MA at Hollywood-Burbank Airport (Bureau d’Archives des Accidents d’Avion)

A Las Vegas, Nevada, hotel chartered Mercer Airlines to fly a group of passengers from Ontario International Airport (ONT), Ontario, California, to McCarran International Airport (LAS). On 8 February 1976, 36326, operating as Mercer Flight 901, was preparing to fly from Hollywood-Burbank Airport (BUR) where it was based, to ONT. The airliner had a flight crew of three: Captain James R. Seccombe, First Officer Jack R. Finger,  Flight Engineer Arthur M. Bankers. There were two flight attendants in the passenger cabin, along with another Mercer employee.

Weather at BUR was reported as 1,000 feet (305 meters) scattered, 7,000 feet (2,134 meters) overcast, with visibility 4 miles (6.4 kilometers) in light rain and fog. The air temperature was 56 °F. (13.3  °C.), the wind was 180° at 4 knots (2 meters per second).

At 10:35 a.m. PST (18:35 UTC), Flight 901 was cleared for a rolling takeoff on Burbank’s Runway 15. While on takeoff roll, Flight Engineer Bankers observed a warning light for engine (inboard, starboard wing). He called out a warning to the Captain, however, the takeoff continued.

Immediately after takeoff, a propeller blade on failed. The intense vibration from the unbalanced propeller tore the engine off of the airplane’s wing, and it fell on to the runway below.

The thrown blade passed through the lower fuselage, cut through hydraulic and pneumatic lines and electrical cables and then struck the engine (inboard, port wing), further damaging the airplane’s electrical components and putting a large hole in that engine’s forward accessory drive case. The engine rapidly lost lubricating oil.

Flight 901 declared an emergency and requested to land on Runway 07, which was approved by the Burbank control tower, though they were informed that debris from the engine was on the runway at the intersection of 15/33 and 07/25. The airplane circled to the right to line up for Runway 07.

Just prior to touchdown, warning lights indicated that the propeller on the engine had reversed. (In fact, it had not.) Captain Seccombe announced that they would only reverse and (the outboard engines, port and starboard wings) to slow 36326 after landing, and the airplane touched down very close to the approach end of the runway.

Because of the damage to the airplane’s systems, the outboard propellers would not reverse to slow the airplane and the service and emergency brakes also had failed. N901MA was in danger of running off the east end of the 6,055 foot (1,846 meters) runway, across the busy Hollywood Way and on into the city beyond.

The flight crew applied full power on the remaining three engines and again took off.  The landing gear would not retract. The electrical systems failed. The engine lost oil pressure and began to slow.

The DC-6 circled to the right again and headed toward Van Nuys Airport (VNY), 6.9 miles (11.1 kilometers) west of Hollywood-Burbank Airport. They informed Burbank tower that they would be landing on Van Nuys Runway 34L which was 8,000 feet (2,438 meters) long. Because of the emergency, the crew remained on Burbank’s radio frequency. The engine then stopped but the propeller could not be feathered.

Bob Hope Burbank irport is at the right edge of this image, and Van Nuys Airport is at the left. Woodly Golf Course is just south of VNY. (Google Earth image)
Hollywood-Burbank Airport (BUR) is at the right edge of this image, and Van Nuys Airport is at the left. Woodley Lakes Golf Course is just south of VNY. (Google Earth image)

Van Nuys weather was reported as 600 feet (183 meters) scattered, 10,000 feet (3,048 meters) overcast, with visibility 10 miles (16.1 kilometers) in light rain, temperature 55 °F. (12.8 °C.). The airliner was flying in and out of the clouds and the crew was on instruments. [1045: “Special, 1,200 scattered, 10,000 feet overcast, visibility—10 miles, rainshowers, wind—130° at 4 kn, altimeter setting—29.93 in.”]

Because of the drag of the unfeathered engine propeller and the extended landing gear, the Flight 901 was unable to maintain altitude with the two remaining engines. The airplane was not able to reach the runway at VNY.

A forced landing was made on a golf course just south of the airport. The airplane touched down about 1 mile south of the threshold of Runway 34L on the main landing gear and bounced three times. At 10:44:55, the nose then struck the foundation of a partially constructed building, crushing the cockpit. All three flight crew members were killed by the impact.

Douglas YC-112A serial number 36326, N901MA, shortly after crash landing at Woodley Golf Course, Van Nuys, California, 8 February 1976. (Bureau d’Archives des Accidents d’Avions)

Both flight attendants were trapped under their damaged seats but were able to free themselves. They and the passenger were able to escape from the wreck with minor injuries.

Los Angeles City Fire Department firefighters attempted to rescue the crew by cutting into the fuselage. Even though the area around the airplane had been covered with fire-retardant foam, at about 20 minutes after the crash, sparks from the power saw ignited gasoline fumes. Fire erupted around the airplane. Ten firefighters were burned, three severely. N901MA was destroyed.

"Feb. 8, 1976: Firemen scatter after saw ignites gas fumes at crash site of DC-6 in Van Nuys. Three trapped crew members of Mercer Enterprises DC-6 charter plane died. Ten firemen were injured." (Boris Yaro/Los Angeles Times)
“Feb. 8, 1976: Firemen scatter after saw ignites gas fumes at crash site of DC-6 in Van Nuys. Three trapped crew members of Mercer Enterprises DC-6 charter plane died. Ten firemen were injured.” (Boris Yaro/Los Angeles Times)

At the time of the accident, YC-112A 36326 was just three days short of the 30th anniversary of its completion at Douglas. It had flown a total of 10,280.4 hours. It was powered by three Pratt & Whitney R-2800-83 AMS, and one R-2800-CA18 Double Wasp engines. All four engines drove three-bladed Curtiss-Wright Type C632-S constant-speed propellers. The failed propeller had been overhauled then installed on N901MA 85 hours prior to the 8 February flight.

The National Transportation Safety Board investigated the accident. It was found that a fatigue fracture in the leading edge of the propeller blade had caused the failure. Though the propeller had recently been overhauled, it was discovered that the most recent procedures had not been followed. This required that the rubber deicing boots be stripped so that a magnetic inspection could be made of the blade’s entire surface. Because this had not been done, the crack in the hollow steel blade was not found.

© 2019, Bryan R. Swopes

12 December 1953

Bell X-1A 48-1384 in flight. The frost band on the fuselage shows the location of the cryogenic propellant tank. (U.S. Air Force)

12 December 1953: On its tenth flight, U.S. Air Force test pilot Major Chuck Yeager flew the Bell X-1A rocket plane to Mach 2.435 (1,618 miles per hour/2,604 kilometers per hour) at 74,700 feet (22,769 meters), faster than anyone had flown before.

After the rocket engine was shut down, the X-1A tumbled out of control—”divergent in three axes” in test pilot speak—and fell out of the sky. It dropped nearly 50,000 feet (15,240 meters) in 70 seconds. Yeager was exposed to accelerations of +8 to -1.5 g’s. The motion was so violent that Yeager cracked the rocketplane’s canopy with his flight helmet.

Yeager was finally able to recover by 30,000 feet (9,144 meters) and landed safely at Edwards Air Force Base.

Yeager later remarked that if the X-1A had an ejection seat he would have used it.

Bell Aircraft Corporation engineers had warned Yeager not to exceed Mach 2.3.

Major Charles E. Yeager, U.S. Air Force, seated in the cockpit of the Bell X-1A, 48-1384, circa 1953. (U.S. Air Force)

The following is from Major Charles E. Yeager’s official post-flight report:

After a normal drop at 31,000 feet, chambers , , and were ignited and [the] airplane was accelerated up to .8 Mach number. A flight path was formed holding .8 Mach number up to 43,000 feet where chamber was ignited and the airplane accelerated in level flight to 1.1 Mach number. A climb was again started passing through 50,000 feet at 1.1 Mach number, 60,000 feet at 1.2 Mach number and a push-over was started at 62,000 feet. The top of the round-out occurred at 76,000 feet and 1.9 Mach number. The airplane was accelerated in level flight up to 2.4 [2.535 indicated] Mach number where all of the rocket chambers were cut. The flight path was very normal and nothing uneventful [sic] happened up to this point. After the engine was cut, the airplane went into a Dutch roll for approximately 2 oscillations and then started rolling to the right at a very rapid rate of roll. Full aileron and opposite rudder were applied with no effect on the rate of roll of the airplane. After approximately 8 to 10 complete rolls, the airplane stopped rolling in the inverted position and after approximately one-half of one second started rolling to the left at a rate in excess of 360 degrees per second, estimated by the pilot. At this point the pilot was completely disoriented and was not sure what maneuvers the airplane went through following the high rates of roll. Several very high ‘g’ loads both positive and negative and side loads were felt by the pilot. At one point during a negative ‘g’ load, the pilot felt the inner liner of the canopy break as the top of his pressure suit helmet came in contact with it. The first maneuver recognized by the pilot was an inverted spin at approximately 33,000 feet. The airplane then fell off into the normal spin from which the pilot recovered at 25,000 feet.

Flight test data from Yeager's 12 December 1953 flight superimposed over a photograph of the bell X-1A. (NASA)
Flight test data from Yeager’s 12 December 1953 flight superimposed over a photograph of the Bell X-1A. (NASA)

The following is a transcript of radio transmissions during the flight:

Yeager: Illegible [inaudible]—gasping—I’m down to 25,000 over Tehachapi. Don’t know
whether I can get back to the base or not.
Chase (Ridley): At 25,000 feet, Chuck?
Yeager: Can’t say much more, I got to (blurry—save myself).
Yeager: I’m—(illegible)—(Christ!)
Chase (Ridley): What say, Chuck?
Yeager: I say I don’t know if I tore anything up or not but Christ!
Chase (Murray): Tell us where you are if you can.
Yeager: I think I can get back to the base okay, Jack. Boy, I’m not going to do that any more.
Chase (Murray): Try to tell us where you are, Chuck.
Yeager: I’m (gasping)…I’ll tell you in a minute. I got 1800 lbs [nitrogen] source pressure.
Yeager: I don’t think you’ll have to run a structure demonstration on this damned thing!
Chase (Murray): Chuck from Murray, if you can give me altitude and heading, I’ll try to check you from outside.
Yeager: Be down at 18,000 feet. I’m about—I’ll be over the base at about 15,000 feet in a minute.
Chase (Murray): Yes, sir.
Yeager: Those guys were so right!
Yeager: Source pressure is still 15 seconds, I’m getting OK now.
Yeager: I got all the oscillograph data switches off. 4 fps camera off, it’s okay.
Bell Truck: Jettison and vent your tanks.
Yeager: I have already jettisoned. Now I’m venting both lox and fuel. Leaving hydrogen peroxide alone.
Bell Truck: Roger.
Yeager: I cut it, I got—in real bad trouble up there.
Yeager: Over the base right now, Kit, at 14,500 feet.
Chase (Murray): I have you.

A North American F-86E-10-NA Sabre chase plane, 51-2848, follows the Bell X-1A as it glides toward Rogers Dry Lake. (NASA)
A North American F-86E-10-NA Sabre chase plane, 51-2848, follows the Bell X-1A as it glides toward Rogers Dry Lake. (NASA)

In his autobiography, Always Another Dawn, NACA test pilot Albert Scott Crossfield wrote:

Probably no other pilot could have come through that experience alive. Much later I asked Yeager, as a matter of professional interest, exactly how he regained control of the ship. He was vague in his reply, but he said he thought that after he reached the thick atmosphere, he had deliberately put the ship into a spin.

“A spin is something I know how to get out of,” he said. “That other business— the tumble—there is no way to figure that out.”

. . . Yeager received many accolades. I didn’t begrudge him one of them. If ever a pilot deserved praise for a job well done, it was Yeager. After that X-1A episode, he never flew a rocketplane again.

Always Another Dawn: The Story of a Rocket Test Pilot, by A. Scott Crossfield with Clay Blair, Jr., The World Publishing Company, Cleveland and New York, Chapter 19 at Pages 183–184.  

Bell X-1A 48-1384 (U.S. Air Force)

The Bell X-1A, 48-1384, was an experimental rocket-powered high-speed, high-altitude research aircraft. It was one of four second-generation X-1s (including the X-1B, X-1D and X-1E), specifically designed to investigate dynamic stability at speeds in excess of Mach 2 and altitudes greater than 90,000 feet. It was a mid-wing monoplane with retractable tricycle landing gear. The airplane was 35 feet, 6.58 inches (10.835 meters) long with a wingspan of 30 feet, 6 inches (9.296 meters) and overall height of 10 feet, 2.37 inches (3.261 meters). The wheelbase, measured from the nose wheel axle to the main wheel axle, was  13 feet, 5.13 inches. (4.093 meters). The main wheel tread was 4 feet, 3 inches (1.295 meters). The X-1A design gross weight was 10,668 pounds (4,839 kilograms).

The X-1A was powered by a single Reaction Motors XLR11-RM-5 rocket engine with four independent combustion chambers. The XLR11 was fueled with ethyl alcohol and liquid oxygen. It produced 6,000 pounds of thrust (26.689 kilonewtons).

The Bell X-1A made its first flight 14 February 1953 with Bell test pilot Jean Ziegler in the cockpit. It reached its highest speed, Mach 2.44 on Flight 10. Its highest altitude was 90,440 feet (27,566 meters) on its 24th flight. On 8 August 1955, while still on board its B-50 drop ship, the X-1A suffered an external explosion. The rocketplane was jettisoned and destroyed when it hit the desert floor.

© 2016, Bryan R. Swopes