These are the image contact sheets for each image resolution of the NASA Dryden MD-11 Propulsion Controlled Aircraft (PCA) Photo Gallery.

You're flying a large transport plane carrying hundreds of passengers and instantly you are unable to control the airplane - your controls system has gone out. As a pilot or a passenger, you hope that this scenario never presents itself, but if it did, what if there was a way to safely land the airplane by using throttles only?

With a system known as Propulsion Controlled Aircraft (PCA) not only is the concept a possibility, but it is a reality. By using a specially designed software system a successful flight test program at NASA Dryden Flight Research Center was accomplished.

The program's humble beginning came from a rough sketch on a TWA napkin that Dryden Engineer, Bill Burcham, drew on a flight to St. Louis for a McDonnell Douglas Aerospace (MDA) meeting. He shared his idea with his traveling companion, Dryden F-15 Project Manager, James Stewart. He thought it was a great idea and within five minutes had outlined a test program. They shared it with the people at MDA the next day and they thought it might work too. With the help of Jim Urnes at MDA, they developed and tested the flight software and managed to squeeze PCA into the already existing F-15 research program.

On April 21, 1993, Gordon Fullerton landed the F-15 twice using the PCA system without using any of the flight controls. Over the course of the program, six other pilots flew the PCA equipped airplane and they were all impressed. The plane flew at various altitudes and in unusual attitudes that might be experienced after a major flight control failure. And in every test, PCA recovered the airplane successfully. On August 29, 1995, Gordon Fullerton once again demonstrated the system in a successful landing using only engine power for control, with the PCA system installed on a McDonnell-Douglas MD-11 transport aircraft.

The success of the program was the result of a partnership between NASA and McDonnell Douglas Aerospace, St. Louis, MO, with Pratt & Whitney together with Honeywell designing the software used in the aircraft's control computer. NASA Ames Research Center, Mountain View, California, assisted in the program by performing simulations.

For the MD-11, the PCA system uses standard autopilot controls already present in the cockpit, together with programming in the aircraft's flight control computers. The aircraft demonstrated software used in the flight control computer that essentially landed the MD-11 without a need for the pilot to manipulate the flight controls and without the use of conventional, hydraulic controls. The PCA concept is simple -- for pitch control, the program increases thrust to climb and reduces thrust to descend. To turn right, the autopilot increases the left engine thrust while decreasing the right engine thrust. Since thrust response is slow, and the control forces are relatively small, a pilot would require extensive practice and intense concentration to do this task manually. Using computer-controlled thrust greatly improves flight precision and reduces pilot workload.

Aircraft manufacturers have decided that a PCA system will be valuable for use in the design of future airplanes. When they incorporate this for future design, it will eliminate the need for a less capable hydraulics-dependent backup flight control system. The PCA, also known as the Engines-Only Flight Control System, is patented and currently seeking potential licensees. The PCA has also been featured in NASA Tech Briefs and was the winner of an Exceptional Award in NASA's Space Act Award program. "Now that the technology is proven, I hope to see it incorporated into future aircraft designs," Burcham stated. "I also hope it never has to be used."