New Tools Developed to Mitigate Physiological Episodes

U.S. Navy photo-illustration by Fred Flerlage

Since the Physiological Episode Action Team (PEAT) has ruled out several causes of physiological episodes (PEs), they are developing tools to improve aircrew awareness and address maintenance-related issues.

Over the past six months, we have had significant success in driving the rate of PEs down. We have accomplished this by making extensive use of data analytics to identify sub-performing system components before they fail thereby preventing PEs in the first place. And when a PE does happen, we have equipped aircrew with tools to help them recognize onset and then mitigate the situation, ultimately ensuring safe recovery,” said Rear Adm. Fredrick Luchtman, Navy lead for the PEAT.

Several types of hypoxia trainers are in development. For example, the Aviation Survival Training Center (ASTC) Jacksonville (JAX) began training with a new, mask-off hypoxia trainer in July that will be used for all Navy and Marine Corps designated aviation personnel flying in multi-place non-ejection aircraft (story on page 22).

The Aircrew Survival Training Center at Naval Air Station Pensacola is demonstrating the newest hypoxia-awareness device for Naval Aviation—the On-Demand Hypoxia Trainer (ODHT) (story on page 23).

Engineers, scientists and medical professionals have ruled out contamination and other potential factors, such as electromagnetic exposure, and found no singular gross contributing factor. However, other factors may play a role in PEs such as maintenance-related issues.

To address this, the Hornet Health and Readiness Tool (HhART), uses data analytics to examine data points from multiple aircraft systems to predict when a system could fail. The computer program is already showing great success in preventing Environmental Control System malfunctions, predicting potential PE-causing aircraft, and has the potential to improve maintenance in other systems as well.

Since PEs happen when two very complicated machines—a naval aircraft and a human body interact asynchronously—teams of engineers are working on how to improve the aircraft and teams of medical professionals are studying the human system.

Physiological monitors are being developed and tested to record and measure what precisely is happening to the human body in different flight conditions.

Researchers across the country are working with aircraft cabin simulators to study how bodies react at different pressure changes. Flight surgeons are trained to handle PEs, so when aircrew do experience significant events, they are treated quickly and effectively.


Since 2017, the phenomenon of PEs has been Naval Aviation’s No. 1 safety priority.

PEs occur when aircrews experience physiological symptoms, which may impair their ability to perform cockpit duties, and can result from many factors, including normal operations in the highly dynamic operating environment, systems malfunctions and various human factors. Symptoms can range from dizziness to degradation of cognitive function, and they pose serious risks to aviators and maintainers.

The PEAT was created in 2017 with personnel and resources from the Naval Air Systems Command, Commander, Naval Air Forces, the Bureau of Naval Medicine and Surgery and the fleet. With the support of experts from industry and NASA, the team coordinates the work of engineers, physiologists and data analysts to employ a methodical, data-driven approach to devise and field best practices and procedures that mitigate the problem while developing long-term solutions.

Using a rigorous root cause corrective action (RCCA) analysis process, the core teams for F/A-18 Hornet, Super Hornet, EA-18G Growler and the T-45 Goshawk training jet determined in 2018 that the onboard oxygen systems showed no contamination. The air was unaffected by asphyxiates, carbon monoxide or other contaminants.

The teams reached that conclusion after a 16-month effort analyzed 21,000 samples taken across 11 sites from aviators’ breathing gas, ground sampling and blood analysis. An independent panel of aeromedical professionals evaluated roughly 1,800 compounds and determined that none of the compounds played a role in any PEs.

While great progress has been made, there are thousands of people from more than 50 organizations including DoD, government, industry, academia, medical and research facilities, along with international partners who continue to focus on keeping aviators safe, so they can focus on the mission.

Written by Andrea Watters, editor of Naval Aviation News magazine.

New Mask-Off Hypoxia Training Delivered

Aviation Survival Training Center (ASTC) Jacksonville (JAX) began training with a new, mask-off hypoxia trainer in July that will be used for all Navy and Marine Corps designated aviation personnel flying in multi-place non-ejection aircraft.

The Normobaric Hypoxia Trainer (NHT) supervisor, communicates with Sailors during training in the newly operational NHT at Aviation Survival Training Center Jacksonville, July 22. (U.S. Navy photos by MC2 Nick A. Grim)

Capt. Theron Toole, then Commanding Officer, Navy Medicine Operational Training Center, and Capt. Leslie Kindling, officer in charge, Naval Survival Training Institute in Pensacola, visited ASTC JAX to observe an initial training session with the newly mission-capable Normobaric Hypoxia Trainer (NHT).

“The NHT provides the most realistic hypoxia training for these aircrew members,” said Kindling, who oversees the Navy’s eight ASTCs.

The NHT simulates the reduced oxygen levels experienced in a depressurized aircraft at altitude, allowing the aircrew to practice their emergency procedures while experiencing the signs and symptoms of hypoxia.

Hypoxia is caused by a lack of sufficient oxygen at the tissue level in the body leading to performance degradation. Symptoms of hypoxia include light-headedness, dizziness, tingling, euphoria and decreased visual accuracy. Training aircrew to recognize the symptoms helps ensure they can take action before progressing to potentially life-threatening situations while in an aircraft at altitude.

“I really felt the effects more this time around, especially feelings of disorientation and difficulty breathing,” said Aircrewman (Mechanical) 2nd Class John Booker, who was taking the hypoxia training qualification for the third time. Aircrew are required to take a refresher course every four years.

The NHT at ASTC JAX is the first operational trainer of its type in the fleet and has replaced the low-pressure chamber that was decommissioned in February 2017. Sailors assigned to ASTC JAX have been at the forefront of implementation and operational testing for the new trainer since its inception in summer 2018.

“As a staff, ASTC JAX became 100-percent qualified in only 18 working days, on top of the already established training schedule,” said Chief Aircrewman (Avionics) Scott Counselman, ASTC JAX leading chief petty officer. “Nothing has been dropped or moved. We began operational testing late last July, and the ASTC staff has been learning new operating procedures, assisting in writing standard operations and safety procedures, and conducting risk management analysis.”

The NHT attempts to simulate pilot and aircrew activities at altitudes greater than 24,000 feet so aircrew become aware of signs and symptoms of hypoxia. (U.S. Navy photos by MC2 Nick A. Grim)

Counselman said once the testing was complete and the procedures validated, the staff qualification process commenced and proceeded at a rapid pace, leading to the introduction of the device to refresher Naval Aviation Survival Training Program classes in July.

With the ASTC JAX NHT now fully functional, the staff will work with the remaining seven ASTCs. Located in Norfolk, Virginia; Cherry Point, North Carolina; Whidbey Island, Washington; Miramar, California; Pensacola, Florida; Lemoore, California; and Patuxent River, Maryland, the ASCTCs are scheduled to become fully operation by summer 2020.

Written by MC2 Nick A. Grim with Naval Air Station Jacksonville Public Affairs.

Hypoxia Trainer: Breath of Fresh Air at Tailhook

Navy Lt. Chris Gilg explains the operation of the On-Demand Hypoxia Trainer (ODHT) to Air Force Capt. Mike Grimmer at the Tailhook Association Convention in Reno, Nev. The ODHT is designed to provide a mask-on breathing experience that is similar to what military aircrew use in flight. (U.S. Navy)

Physiology experts were on hand at the annual Tailhook Association Convention Sept. 5-7 providing a demonstration of the newest hypoxia-awareness device for Naval Aviation—the On-Demand Hypoxia Trainer (ODHT).

Hypoxia is a condition in which the body is deprived of adequate oxygen supply and can adversely affect aircrew if they are not properly trained to recognize the symptoms of air hunger.

All naval aviators and aircrew must complete refresher physiology training at least every two years and must familiarize themselves with potential hazards in flight including decreased levels of oxygen.

“The ODHT is great because it reduces oxygen levels and gives the user the feeling of difficulty breathing,” said James Netherland, an electrical engineer for the new system that helps train aircrew.

Lt. Chris Gilg, a naval aerospace physiologist at the Aircrew Survival Training Center at Naval Air Station Pensacola, said the ODHT changes the game when it comes to recognizing hypoxia hazards while in flight.

“We expect aircraft to perform in a certain way,” said Gilg. “When it doesn’t, however, there is a chance that hypoxia can set in; we can train aircrew to be able to recognize the symptoms in themselves and others.”

At Tailhook, attendees volunteered to breathe through a mask that delivers reduced oxygen concentrations like those they would expect to experience at altitude, and then provided feedback that designers will consider in the continued development of the ODHT.

“Bringing the system to Tailhook, we get to network with the aviators and to allow them to test this new device,” said Gilg. “It’s important for them to see there is work being done to make the training more realistic, with the on-demand system here.

“We’ve also been training students with it and based on the reliability it’s shown thus far, and the feedback that we’ve gotten, this system is what it actually feels like to breathe in the aircraft,” he said.

During Tailhook, the team ran hypoxic profiles with 17 aviators to gain feedback on the system. In general, the aviators reported that the ODHT provided a breathing experience that was similar or slightly smoother than the inhalation and exhalation feel in their aircraft.

In some instances, the aviators specifically noted that they could not detect a noticeable difference between the breathing experience on the device and on the jet.

Several aviators reported that the ODHT provided a better experience than the current training device, the Reduced Oxygen Breathing Device.

The ODHT is in the testing phase and the Navy is hoping to see it fully implemented in 2021.

Written by Naval Aviation Enterprise Public Affairs.