The Controlled Impact Demonstration, also known as “the Crash in the Desert” was a joint project between NASA and the Federal Aviation Administration (FAA). The idea was to intentionally crash a remotely controlled Boeing 720 airplane in order to acquire data and test new technologies to aid passenger and crew survival. As we all know, airplane crashes, often bring fatalities. Still, there have been a number of airplane crashes in which all or most of the plane’s occupants survived the crash. The point of “the crash in the desert” was to learn from the vent, and hopefully make a way for more people to survive the crash.
The Controlled Impact Demonstration took more than four years of preparation by NASA Ames Research Center, Langley Research Center, Dryden Flight Research Center, the FAA, and General Electric to pull off. Then, because obviously they did not have an unlimited supply of planes, they held several test runs to make sure they had the right “crash” conditions to learn the most about crashes. Finally, on December 1, 1984, the plane was actually crashed. The test went pretty much according to plan and produced a large fireball that required more than an hour to extinguish. With that in mind, a casual observer would assume that everyone would have died, but the FAA concluded that about one-quarter of the passengers would have survived!! It also determined that the antimisting kerosene test fuel did not sufficiently reduce the risk of fire. Antimisting kerosene (AMK) is “a jet fuel containing an antimisting additive. This additive, a high-molecular-weight polymer, causes the fuel to resist atomization and liquid shear forces, which also affect flow characteristics in the engine fuel system.” Finally, it determined that several changes to equipment in the passenger compartment of aircraft were needed…which is probably one of the most important findings of the demonstration. NASA also concluded that a head-up display and microwave landing system would have definitely 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. Once aloft, the plane made a left-hand departure and climbed to an altitude of 2,300 feet. The plane 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 of AMK and all engines ran from start-up to impact. The total 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 above ground level (AGL), the airplane turned slightly to the right of the desired path, entering into a situation known as a Dutch roll. Slightly above that decision point at which the pilot was to execute a “go-around” maneuver. 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. At this point, the data acquisition systems had been activated, and the plane was committed to impact. That situation had to have almost a strange feeling to it…that point of knowing that the plane was going to crash and knowing that the crash was exactly what you wanted it to do. Then the plane contacted the ground, left wing low, at full throttle, with its nose pointing to the left of the center-line. The original plan was 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 (called “Rhinos” due to the shape of the “horns” welded onto the posts).” The Boeing 720 had a surprise in store for the researchers, when it 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 1/3 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.”
The actual impact proved that the antimisting additive they had tested was not going to prevent a post-crash fire in all situations, but the reduced intensity of the initial fire was attributed to the effect of the AMK. FAA investigators estimated that 23% to 25% of the aircraft’s full capacity of 113 people could have survived the crash. Now that is saying something, considering the way the crash looked to observers. “Time from slide-out to complete smoke obscuration for the forward cabin was 5 seconds; for the aft cabin, it was 20 seconds. Total time to evacuate was 15 and 33 seconds respectively, accounting for the time necessary to reach and open the doors and operate the slide.” The FAA instituted new flammability standards for seat cushions which required the use of fire-blocking layers as a result of analysis of the crash, resulting in seats which performed better than those in the test. From this crash demonstration, came the implementation of a standard requiring floor proximity lighting to be mechanically fastened, due to the apparent detachment of two types of adhesive-fastened emergency lights during the impact. In addition, federal aviation regulations for flight data recorder sampling rates for pitch, roll, and acceleration were found to be insufficient. NASA determined that at the point of impact, the piloting task workload unusually high, which might have been reduced through the use of a heads-up display, the automation of more tasks, and a higher-resolution monitor. The use of a microwave landing system to improve tracking accuracy over the standard instrument landing system was also recommended. The Global Positioning System-based Wide Area Augmentation System came to fulfill this role.