Are You Ready for Hypoxia? What Bizav Pilots Need to Know

Of all the major potential safety threats that aviation navigates, perhaps none can be as stealthy and deadly as hypoxia – a shortage of oxygen in the human body, often resulting in reduced functional ability.

Veteran pilots and industry experts say awareness, planning and training are critical to surviving this life-threatening condition, which can stem from a variety of causes.

Plan to Breathe

In January 2003, the pilot of a Piper PA-28R poorly planned and poorly prepared for a flight from Longmont, CO, to Las Vegas. The unpressurized aircraft without supplemental or portable oxygen flew above 12,500 feet for more than two hours, and 16,000 feet for about 45 minutes (the latter of which was above the type’s service ceiling). During this time, air traffic control provided several heading corrections for the flight, and the pilot acknowledged being significantly off course.

After three and a half hours, the aircraft began to experience fuel exhaustion. Being forced down into breathable air, the pilot then realized the severity of the issue and declared a “mayday” to the FAA’s Denver Air Route Traffic Control Center (ZDV). The aircraft crashed minutes later near La Sal, UT, killing the pilot and its three passengers.

The NTSB cited hypoxia as a contributing factor to both the flight’s navigation issues and poor fuel management.

Bizjets Are Not Immune

Adequate planning doesn’t necessarily keep you in the clear. In June of 2023, after departing Elizabethton, TN, and climbing through 26,600 feet, a Cessna Citation 560 did not respond to ATC instructions to climb higher.

The jet continued toward its programmed destination of New York’s Long Island MacArthur Airport (ISP) at its planned altitude of 34,000 feet. Still following the programmed flight plan, the airplane turned to line up for final approach at ISP, but did not descend. Instead, it continued at cruising altitude in a southwest direction.

NORAD sent six F-16s to intercept. After making visual contact and noticing the pilot slumped over, the Citation began a spiraling descent, crashing into a mountain near Montebello, VA, and killing all four on board.

The NTSB found that cabin depressurization led to hypoxia and pilot incapacitation.

Training Is a Must

Training is offered at many facilities across the United States. “We want them to recognize their own symptoms and call attention to it,” explained NBAA member Brian Hayvaz, vice president of operations for Aircare FACTS Training.

Classroom training and simulations typically include working inside a mixed gas chamber. This chamber can recreate various scenarios, including different altitudes and slow onset hypoxia or rapid decompression.

Learn Your Personal Symptoms

Knowing how your body reacts will be a big part of a proactive response, and will avoid the common challenge of dismissiveness, said NBAA member Steven C. Martin, manager of aerospace physiology operations at the University of North Dakota’s John D. Odegard School of Aerospace Sciences.

“A big problem with slow onset hypoxia, especially in single-pilot operations, is that they pass it off as something else,” Martin said. “Not enough coffee, not enough sleep, coming down with something, etc., and they assign that problem to those symptoms … eventually becoming incapacitated.”

“The range of symptoms we are able to demonstrate during the live hypoxia training vary greatly,” said Hayvaz. “It is a very personal response. From confusion and dizziness, numbness and tingling in fingers, to lethargy, euphoria and even combative behavior.”

Chief Pilot Melanie Hight, an NBAA member and director of safety at OpenAir, said she was shocked when she first learned just how subtle those early signs of hypoxia can be – “however I am now grateful that I am familiar with them and can recognize them.”

A Team Effort

One major value of this training is not just identifying your own hypoxia, but also that of fellow crew members.

It may mean “watching your left seat pilot think he or she is doing just fine, but you notice a complete change in mannerisms or ability, and they don’t know it,” said Hayvaz. “It becomes a great team building exercise. If you miss the symptoms … it could end in disaster.”

The Altitude Misconception

“People guess hypoxia becomes a threat at 15,000, 20,000 or even 25,000 feet,” Martin said. “That’s a common misconception, as a majority of events happen below 10,000. There are several potential sources or causes of hypoxia in flight, including, but not limited to, carbon monoxide (CO) or other fumes, Martin said. “On approach, becoming hypoxic from smoke or fumes, or even CO from the aircraft in front of you while taxiing, are all quite common.”

Who Should Train

Of course, the need for training is not just limited to pilots. “For cabin crew it is a bit different,” Hayvaz said. “Their procedures are a bit more nuanced, having to deal with passengers. But the endgame is the same: mask on NOW.”

Indeed, no one is exempt. “It’s prudent for every pilot to pursue hypoxia-related training at some point in their career,” Hight added.

“I think what surprises people the most is how quickly the symptoms can creep up on them,” Hayvaz said. “Most people think they can fight their way through the symptoms…believe me, they cannot! Even the most robust and physically fit individual will succumb.”