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February 17, 2020

Controlled Impact Demonstration: In 1984, NASA Made Airliners Safer by Crashing a Boeing 720

The Controlled Impact Demonstration (or colloquially the Crash In the Desert) was a joint project between NASA and the Federal Aviation Administration (FAA) that intentionally crashed a remotely controlled Boeing 720 aircraft to acquire data and test new technologies that might help passengers and crew survive. The crash required more than four years of preparation by NASA Ames Research Center, Langley Research Center, Dryden Flight Research Center, the FAA, and General Electric. After numerous test runs, the plane was crashed on December 1, 1984. The test went generally according to plan, and produced a spectacular fireball that required more than an hour to extinguish.

The FAA concluded that about one-quarter of the passengers would have survived, that the antimisting kerosene test fuel did not sufficiently reduce the risk of fire, and that several changes to equipment in the passenger compartment of aircraft were needed. NASA concluded that a head-up display and microwave landing system would have helped the pilot more safely fly the aircraft.

On the morning of December 1, 1984, the test aircraft took off from Edwards Air Force Base, California, made a left-hand departure and climbed to an altitude of 2,300 feet (700 m). The aircraft was remotely flown by NASA research pilot Fitzhugh Fulton from the NASA Dryden Remotely Controlled Vehicle Facility. All fuel tanks were filled with a total of 76,000 pounds (34,000 kg) of AMK and all engines ran from start-up to impact (flight time was 9 minutes) on the modified Jet-A. It then began a descent-to-landing along the roughly 3.8-degree glideslope to a specially prepared runway on the east side of Rogers Dry Lake, with the landing gear remaining retracted.

Passing the decision height of 150 feet (46 m) above ground level (AGL), the aircraft turned slightly to the right of the desired path. The aircraft entered into a situation known as a Dutch roll. Slightly above that decision point at which the pilot was to execute a “go-around”, there appeared to be enough altitude to maneuver back to the center-line of the runway. The aircraft was below the glideslope and below the desired airspeed. Data acquisition systems had been activated, and the aircraft was committed to impact.

The aircraft contacted the ground, left wing low, at full throttle, with the aircraft nose pointing to the left of the center-line. It had been planned that the aircraft would land wings-level, with the throttles set to idle, and exactly on the center-line during the CID, thus allowing the fuselage to remain intact as the wings were sliced open by eight posts cemented into the runway. The Boeing 720 landed askew. One of the Rhinos sliced through the number 3 engine, behind the burner can, leaving the engine on the wing pylon, which does not typically happen in an impact of this type. The same rhino then sliced through the fuselage, causing a cabin fire when burning fuel was able to enter the fuselage.

The cutting of the number 3 engine and the full throttle situation was significant as this was outside the test envelope. The number 3 engine continued to operate for approximately ⅓ of a rotation, degrading the fuel and igniting it after impact, providing a significant heat source. The fire and smoke took over an hour to extinguish. The CID impact was spectacular with a large fireball created by the number 3 engine on the right side, enveloping and burning the aircraft. From the standpoint of AMK the test was a major set-back. For NASA Langley, the data collected on crashworthiness was deemed successful and just as important.


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