October 3, 2012
By Jim Moore
A Boeing 727 was crashed for science and television in the Mexican desert, and the television show airs Oct. 7 on Discovery Channel. Photo courtesy Discovery Channel.
Veteran pilot Chip Shanle maintained a stable descent at 1,000 feet per minute, with no intent to pull up. The flight crew on board had bailed out over the Mexican desert with two minutes left in the flight, pausing just long enough to arm a fail-safe system designed to einsure the Boeing 727 would crash safely on the designated spot.
Despite a mechanical problem that forced Shanle to use a slower chase plane than planned, the Boeing crashed more or less on target. The fruits of that effort include a wealth of data for science, and a television special that will air Oct. 7 on the Discovery Channel.
“You know, being that close to a 727, in formation, and flying it and then watching it hit, because that’s what our job as pilots is all designed not to do, is to break up an airplane, it was pretty strange, actually,” Shanle recalled. “Especially that close.”
Four years of careful planning went into the April experiment. Shanle, a retired U.S. Navy test pilot, airline pilot, and author, is president of Broken Wing, a production company founded by Shanle and fellow test pilots to handle the aviation side of a complex operation. He said the crash had a serious purpose that hit close to home for many on the team who have lost loved ones and comrades in aircraft crashes.
“We set upon doing this to try to make things safer,” Shanle said. “Not just do something wild.”
‘A piece of the puzzle’
Gathering the data that will help aircraft designers “make things safer” was the job of four scientists, including Cindy Bir of Wayne State University, who specializes in studying the mechanisms of injury in crashes. Bir said three crash test dummies were deployed in the ill-fated airliner, two of them placed together to compare the effect of braced versus unbraced crash positions. While the data is still being analyzed, Bir was struck by the difference bracing for impact can make. Specifically, the brace position significantly reduced the “bending moment” in the lumbar spine.
“Going in I didn’t expect to see that,” Bir said. She had expected to find more force exerted on the neck of an unbraced passenger. “The lower back region really had the highest loads.”
Crash test dummies collected data as the 727 hit the Mexican desert. Photo courtesy Discovery Channel.
Bir said the science team will publish journal articles and plans presentations of their findings, something they will be cleared to do after the television show airs. Up to now, Discovery Channel has kept a tight lid on the data, and footage, though a spectator’s video posted to YouTube offered a sneak peek of the crash—from a distance, soon after it happened.
While the mainstream media has pounced to conclusions (back seats are safer, for example) from the experiment, “every crash is unique,” Bir said, and the findings may not support such sweeping conclusions. While the crash test dummy in the back of the cabin was subjected to forces less likely to injure, that was a product of how the crash itself was designed.
“It’s a piece of a puzzle,” Bir said of the overall findings. “Obviously, we’re not going to jump to conclusions from this one test.”
The experiment nonetheless added a significant trove of real-world data that is impossible to gain from computer simulations, Bir said.
“We really did get some amazing data that we’ve never had before out of this,” Bir said.
‘A pretty tall order’
Shanle said the science team gave a tall order: create a crash that produces a range of potential injury, from fatality to walk-away. The airliner had to break up, but could not be allowed to burn, and needed to crash on a small target.
“We all kind of laughed, to be honest,” Shanle said. “That’s a pretty tall order.”
Mexican aviation officials needed reassurances that the aircraft would not be allowed to fly without a crew on board near populated areas, which meant a flight crew had to be on board until almost the last minute. As they bailed out, the crew armed a custom-made device dubbed “Deep Six” by the team, which includes several Navy veterans, fashioned with components designed for unmanned aerial vehicles. “Deep Six” provided only pitch control, a last-ditch fail-safe that would drive the airplane down to prevent it from straying outside the designated range in case of radio failure. The primary controls Shanle manipulated included off-the-shelf parts from the hobby industry, cobbled into a redundant system designed by the Broken Wing team.
Shanle said the mission profile needed by the science team translated into a relatively flat pitch attitude at impact, with two of the three engines at idle. In the desert heat, that would preclude an unwanted climb.
Ironic as it may seem, extensive safety precautions were taken before, during, and after the crash flight. Photo courtesy Discovery Channel.
Shanle said accuracy suffered a little with a last-minute mechanical problem that put the Aermacchi SF.260 chase plane out of commission. With time running out, and postponement not an option, Shanle jumped in a secondary chase plane—a Cessna 337 Skymaster—sacrificing speed, and the ability to chase the doomed airliner a little closer.
The flight engineer and first officer, each with a jumpmaster to assist in a tandem exit, bailed out after climbing to 6,000 feet. The captain and his jumpmaster set the throttles and jumped after lining up the final approach, passing in sight of Shanle in the Cessna with “a wide grin” visible.
“The airplane was in fantastic shape. I actually felt kind of guilty whacking it,” Shanle recalled.
The crash, captured from many angles, was cause for celebration—nearly unique, in that respect, in the history of airlines hitting the ground too hard. NASA conducted a similar exercise in 1984, but the cost and complexity of crashing a full-size airliner makes it unlikely to ever be commonplace.
“The amount of data that they’re going to get is amazing,” Shanle said.
Bir said watching the crash was “surreal,” and the survival of the various sensors was a great relief.
“We only had one shot to get it,” Bir said. “If we missed it, we missed it.”
AOPA Online Associate Editor Jim Moore joined AOPA in 2011 and is an instrument-rated private pilot who enjoys competition aerobatics.
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