The Curse of the Cargomaster
Readied to transport the first U.S. ICBMs, the Douglas C-133 had a peculiar habit. It kept crashing.
- By John Sotham
- Air & Space magazine, September 2010
(Page 2 of 6)
Sandstrom shuts down the ground unit, and the pitch of the big diesel engine spirals down. The shouting stops, and as the men resume talking, the discussion turns to what the crews who flew and maintained the big airlifter inevitably end up talking about.
It was another cool Dover morning, April 13, 1958, when a four-man crew from the 39th Air Transportation Squadron rode the flightline van to C-133A tail number 40146. At 8:28 a.m., 40146 lifted off the runway behind what is today the museum hangar. The crew transmitted routine messages at 8:34 and 8:40. Three minutes later and 26 miles south of the base, the airplane fell inverted from the sky into Ellendale State Forest.
The Air Force grounded the C-133 fleet. It had been only 24 months since the first flight at the Douglas facility in Long Beach, California. Acquired under a new system of concurrent development and production, an Air Force attempt to limit procurement costs and delays, the C-133 program had no prototype phase; the aircraft had gone from drawing board to production line. Although the first eight airframes underwent flight tests at Edwards Air Force Base in California, most of the testing coincided with aircraft deliveries to operational units. Modifications were made throughout the Cargomaster’s service life.
A team of accident investigators assembled at Dover. Most of their theories centered on a nastiness the Cargomaster had exhibited during its earliest tests: The aircraft gave its pilots virtually no warning when it stalled. The buffet that accompanies a stall, which in most aircraft serves as advance notice, arrived in the Cargomaster almost simultaneously with the stall itself. Tests also showed that abnormal airflow over the horizontal stabilizers could render the elevators ineffective. In early 1957, a fix was incorporated into the eighth aircraft built and retrofitted on the previous seven: a horizontal “beaver tail” that extended behind the vertical stabilizer helped to keep the airflow over the control surfaces smooth and to counter the airplane’s tendency in a descent to tuck under. But 40146 already had those modifications. Why did it crash? Although the investigators couldn’t report a definitive cause, they identified 17 deficiencies in the C-133’s control system that could have been contributing factors, and a team of Douglas engineers traveled to Dover to correct them. A month later, the airplane resumed operation, and all was well—for three years.
The next two Cargomasters to go down simply disappeared during overwater passages. The first, an aircraft headed for Midway Island, and then home to California’s Travis Air Force Base, left Tachikawa Air Base in Japan one minute before midnight on June 9, 1961. Twelve minutes after a normal takeoff, followed by a routine radio call, it was gone. Less than a year later, on May 27, 1962, number 71611 departed Dover, then dropped from the radar shortly after the pilot reported passing through 13,000 feet. In the two accidents, 14 crew members died.
The C-133 began to get a reputation, and crews listened intently for any signal of a stall, especially during climbout when the aircraft, full of fuel, was heaviest. Sandstrom and other Cargomaster crewmen found that the airplane had a subtle stall warning device: the windshield wipers. “When we’d enter a stall, the windshield wiper would vibrate,” Sandstrom says. “If you saw that, you better be putting the nose down.”
But what if, on the next mission, you missed the Cargomaster’s whisperings? What would it feel like to be pinned against the straps, watching helplessly as the ocean filled the windscreen?