Professor explains how pilots can miss signs of hypoxia

At about 30K feet, a pilot’s ability is ‘measured in seconds’

DAYTONA BEACH, Fla. – It will still take some time before the National Transportation Safety Board can determine what caused a Florida-based plane to crash in Virginia.

The plane was registered to Encore Motors in Melbourne, Florida.

The Cessna Citation took off from Elizabethton Municipal Airport in Tennessee Sunday afternoon headed for MacArthur Airport on Long Island, New York.

It would eventually fly into restricted airspace over Washington, D.C.

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Six F-16 fighter jets were scrambled to intercept the rogue aircraft after air traffic control could not communicate with it.

According to reports, the pilots of the fighter jets saw the pilot of the Cessna slumped over in the cockpit.

Many in the aviation world speculate the leading cause of this tragedy may have been hypoxia, which is a loss of oxygen.

We reached out to Embry Riddle Aeronautical University in Daytona Beach to get a better understanding of exactly how and why hypoxia happens.

Scott Wagner is an assistant professor of aeronautical science at ERAU and a pilot himself.

Professor Wagner started our conversation by saying, “Any time there is a loss in aviation we all feel the pain and the grief that goes with that.”

I asked Wagner to describe the symptoms a person who has hypoxia might exhibit.

“By definition, hypoxia is lack of oxygen in our body. Generally, above 10,000 feet, we enter what we call a physiological deficient zone,” Wagner explained. “As we climb, continue to climb in the atmosphere, our body’s exposed to less and less partial pressure of that oxygen and we start to feel the effects (...) it affects our tissues, our organs, also affects our brain and our eyes.”

He also said symptoms can vary.

“Some of the symptoms that we might feel would be dizziness, numbness, perhaps tingling or loss of visual acuity, euphoria is a big one,” Wagner explained. “As pilots, we’re trained to recognize some of the symptoms and then to correlate that with the fact that we might be getting hypoxic.”

Wagner said symptoms of hypoxia can occur in a matter of minutes.

“At 18,000 feet for example, the partial pressure of air and oxygen is about half of what it is on sea level,” he explained. “Typically, the FAA charts equate that to about 20 minutes time with useful consciousness.”

Wagner said once an aircraft climbs about 30,000 feet, a pilot’s ability to function usefully is then measured in seconds. Beyond that point, an individual may no longer be capable of taking normal corrective action.

While our bodies are telling us something unusual is happening, Wagner says those symptoms could be ignored because pilots are busy.

“The quicker the rate of climb, the less time you may have to recognize the symptoms. Also in a climb scenario, pilots are busy. They are talking to air traffic control, they’re doing their after-takeoff checklists, climb checklists, crews’ checklists, air traffic control might give them new routing, a new frequency to talk to, a different controller, maybe a different squawk code,” Wagner said. “So, they’re busy during this time, so it’s easy to get distracted.”

Wagner said if there is a problem at high altitude in the cabin, the pilot typically receives a warning, yet they could still miss many of the body’s warning signs.

“We’ve got a red warning light, a yellow annunciator light directing him to what the problem is,” he explained.

Sadly, it may be difficult to determine exactly what happened in this case.

Investigators described the wreckage as highly fragmented and piecing together what happened will be a delicate process.

If you would like to hear the entire interview with Wagner — including what he has to say about the similarities to this crash and the Learjet crash of Bay Hill resident and PGA golfer Payne Stewart in 1999 — watch it in the video player at the top of this story.

You can listen to every episode of Florida’s Fourth Estate in the media player below:

About the Author:

Ginger Gadsden joined the News 6 team in June 2014 as an anchor/reporter. She currently co-anchors the 4 p.m. 5:30 p.m. and the 7 p.m. newscasts.