High-Altitude Suits Keep Pressure on Pilots

John Roach
for National Geographic News
September 19, 2006
Thank Jim Sokolik and other life-support technicians for keeping the pilots of NASA's ER-2 high-altitude research aircraft safe and under pressure as the planes head into the upper reaches of Earth's atmosphere.

Sokolik heads the High Altitude Life Support Team at NASA's Dryden Flight Research Center in Edwards, California (California map).

He prepares and maintains the full-pressure suits that inflate around pilots and keep their bodies under sufficient air pressure during flight emergencies.

Without the extra protection, a pilot would die within minutes, should the first line of defense—the pressurized cockpit—fail.

"As you go up in altitude, pressure decreases," Sokolik explained.

ER-2 pilots routinely fly above 63,000 feet (19,200 meters) to study hurricanes, forest fires, atmospheric pollution, and other disasters. (Related: "Hurricane Plane Flies Into Storms to Sharpen Forecasts" [June 2006].)

At that height, oxygen escapes from blood the same way the gas escapes boiling water.

"That's where the suit comes in," Sokolik said.

Sensors on the suit detect changes and automatically adjust pressure within the suit to keep pilots healthy and safe.

Suiting Up

While pressure suits make high-altitude flight safer, wearing them is an exercise in patience and discipline, Sokolik says.

Although modern suits are lightweight and designed for increased pilot movement and comfort, the entire getup—including helmet, boots, and gloves—weighs about 35 pounds (16 kilograms).

When the suits fully inflate, they are rigid and tough to maneuver, says David Wright, one of the Dryden center's ER-2 pilots. Flying the plane takes effort.

"[The suit] becomes very, very restrictive," he said. "But it saves your life, so you're able to put up with that."

Because the suits are custom-fitted, pilots need to keep their weight within a ten-pound range on a year-round basis.

Starting on the day before a flight, pilots also have to watch their diets extra closely. "They stay away from greasy food or foods that have a tendency to upset the stomach," Sokolik said.

That's because the pressure suits are equipped with a plumbing system to pass liquid human waste, Sokolik says, but solid waste is a different matter. And missions can last up to ten hours.

Once a mission is a go, Sokolik meets the pilot about an hour and a half before takeoff to dress the pilot—which takes about 15 minutes—and run the pilot and suit through safety checks.

The gloves reduce dexterity by about half, so suited-up pilots require help to strap in to the cockpit, Wright, the pilot, says.

Inside the cockpit, hoses supply a steady flow of oxygen to the flight helmet and of cool air to ventilate the entire suit assembly.

A small check valve in the bottom of the helmet allows a special tube to be inserted that allows the pilots to eat or drink during a flight. Water comes in plastic bottles, while food is stored in toothpaste tube-like containers.

Since everything the pilot eats has to go through a tube, food must be in a semi-liquid form, Sokolik said—"literally pureed meats and fruits and puddings."

Wright, the pilot, said some of the food is "actually pretty good."

Among his favorites is cherry pie, which he says tastes exactly like the real thing. But not all tube food is quite so appealing.

"One in particular is hideous—bacon, fries, and cheese in pureed form. It's disgusting. All the grease collects in the top of the tube, and that's what you get on the first squeeze," he said.

Safety Record

The pressure suits are designed only as a last line of defense. In 20 years with the High Altitude Life Support Team, Sokolik has had a suit go operational on a pilot only twice, he says.

On both occasions, cabin pressure suddenly dropped at moderate altitudes—between 35,000 and 40,000 feet (10,700 and 12,200 meters).

The suits "got a little puffy," Sokolik said. But within minutes circuit breakers were reset and the cockpit pressure returned to normal.

"Those almost basically don't count, but those are the two experiences I've had and the only two I ever want," he said.

Wright, the pilot, says he had a suit go fully active on him when he was flying the ER-2's cousin, the U2 spy plane, on a mission in Operation Desert Storm, the 1991 U.S.-Iraq conflict.

His cockpit slowly lost air pressure, and the suit gradually inflated to compensate, eventually going fully rigid.

Fortunately, Wright says, the plane was on autopilot. All he had to do was direct the autopilot to return to base. Once the plane descended, the suit deflated.

"The suit did its thing," he said.

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