PENSACOLA, Fla. - A Navy F-14 Tomcat took off and zoomed almost straight up, but the pilot became disoriented in a cloud and the jet plunged into a Nashville neighborhood.
The fiery 1996 crash killed three people on the ground, as well as the pilot and his back-seat crew member.
The spatial disorientation, or vertigo, suffered by the pilot is very common and causes accidents that cost the U.S. military more than $300 million and about 30 lives every year, according to Capt. Angus Rupert of the Naval Aerospace Medical Research Laboratory.
"If you were to experience disorientation while you were walking around here, you'd call a doctor," Rupert said. "In the aviation environment, it's absolutely, perfectly normal."
Rupert is developing for NASA a system designed to counteract that disorientation. In addition to crash prevention, it could give pilots and astronauts a new way to obtain navigation or target information, and eventually may aid people who are blind, deaf or lose their sense of balance as they age, he said.
Follow the vibrations
The Tactile Situation Awareness System relies on the sense of touch, allowing pilots to figuratively fly by the seat of their pants.
Rupert has developed a vest linked to a plane's instruments, but a full torso suit may be the final configuration. If the plane leaves straight and level, the pilot feels a vibration to indicate which way is down.
The idea first came to the Canadian-born flight surgeon during a
naked sky dive in 1974 when he was a student at the University of Illinois. He realized he was getting a lot of sensory information from his bare skin, just like a bird gets from its feathers.
Rupert later earned a Ph.D. in neurophysiology from Illinois while also working on his medical degree at the University of Toronto, commuting in a plane he used for his sky diving school.
He then began touring air museums and looking for a place to do research. While visiting the National Museum of Naval Aviation at Pensacola Naval Air Station, he came across the aerospace medical lab and signed up.
Ever since, Rupert has focused on disorientation.
A pilot can fly perfectly well until losing sight of the horizon, such as at night or in clouds. The pilot's brain still gets balance data from the inner ear and skin-muscle-joint system, but it is distorted by acceleration forces. They make it feel like the plane is climbing when it is not.
That's what happened in Nashville, Rupert said. The pilot had the illusion the plane was still nose-up and mistakenly went into a dive thinking he was leveling off.
Navy officials blamed the crash on pilot error. They said Lt. Cmdr. Stacy Bates lost control of the plane because he made a prohibited, too-steep climb after takeoff, thereby becoming disoriented.
Instruments were invented for such situations but can help only if the pilot is looking at them. A momentary distraction can spell trouble.
"You have to think about it, and there is the real problem," Rupert said. Thinking takes time, and even split seconds can mean disaster. No thinking is needed for a touch-and-feel system.
"You put your finger in the fire, you're going to pull it back," Rupert said. "You have this reflex that helps save you."
Retired Capt. Jim Baker, a medical doctor at NASA's Johnson Space Center in Houston, tried Rupert's vest in 1996 when he was a test pilot at the Patuxent River Naval Air Test Center in Maryland. He flew approaches, rolls and loops from the back of a plane with his canopy covered and all instruments removed, relying on the vest to tell him up from down.
Army tests positive
"It's very basic and very simple and very intuitive," Baker said. "There is no learning process. You just do it."
Climbing in a loop, the vibrations moved up his back and then to his shoulders when he reached the top upside down. The vibrations moved down his chest while flying the back side of the loop.
Army helicopter pilots tested a more elaborate version about a year ago. Linked to a satellite navigation system and other instruments, the vest provided altitude, rate of movement and directional data through changes in the intensity and frequency, as well as the direction, of the vibrations.
Maj. Steven Gilreath, chief of flight systems for the Army Aeromedical Research Laboratory at Fort Rucker, Ala., said he could hold a hover at a fixed place and altitude without drifting, and then fly to another spot several feet away while blindfolded. Those capabilities could dramatically improve safety in bad weather and at night, he said.
Further modifications could alert a pilot of an enemy missile or plane and its direction and distance, keep them pointed at a target or warn they are getting too close to another aircraft, Rupert said.
Fatalism rules the day
NASA is interested in it for shuttle landings, to help astronauts keep oriented during spacewalks and for a civilian version of the military's V-22 Osprey vertical takeoff plane.
The Joint Strike Fighter program also has provided some funding, but Rupert said getting development dollars has been a struggle because many in the military accept disorientation crashes as a cost of doing business.
Initially a skeptic, Gilreath has become an ally.
"I'm trying to plug it all I can," he said. "I've lost too many friends through the years to accidents that I think a system like this could have prevented."