Working at the intersection of cockpit environment and training USAFSAM leverages research to develop environmental and training solutions for optimal pilot performance. Chuck Weirauch reports.

The US Air Force F-22 Raptor advanced interceptor fleet is scheduled to receive new automatic backup oxygen systems by the second quarter of 2015 and it would seem that pilot hypoxia problems with that aircraft will be finally resolved. The current pilot-activated backup oxygen systems were installed earlier in response to a 2012 investigation of pilots experiencing hypoxia-like oxygen deprivation symptoms leading to a fatal crash in 2011 and a grounding of the F-22 fleet. The new system won't call for any action by the pilot.

The failure of the original F-22 oxygen system emphasizes the point that a cockpit environment issue thought to be to be fully understood and researched still needs more study, with a potential need for more hypoxia training for aircrews.

Hypoxia Training

Dr. Ryan Mayes, Senior Epidemiologist for 771th Human Performance Wing's School of Aerospace Medicine (USAFSAM), Department of Aeromedical Research, at Wright Patterson Air Force Base in Ohio was one of the Air Force's investigators involved with the F-22 oxygen system failure study. He pointed out that one area of current research in his department is to investigate is whether Reduced Oxygen Breathing Devices (ROBDs) are successful training analogs for a true hypobaric exposure in an altitude chamber.

But Mayes also feels that training and research should not simply focus on hypoxia and oxygen deprivation. Other aspects of human respiration at altitude need to be studied as well, such as high and low levels of carbon dioxide in the bloodstream that are a result of strained breathing under G-loading. That is because one of the major contributors to pilot distress that was found during the F-22 investigation was the actual work of breathing under G-loading, Mayes explained. A related finding was that the pilot's upper pressure anti-G garment was retaining air, and that made it more difficult for the pilot to breathe, he added.

"Asking an impaired pilot to determine whether he is impaired because of hypoxia or oxygen deprivation is like asking a drunk driver whether he is too drunk to drive," said USAFSAM Senior Research Physiologist Dr. Bruce Wright. "We need realistic training, but we also need to do some research to provide the pilot with a reliable indicator with an objective measure of his physiological state. Training is good, but it has to be realistic, and my take is that an altitude chamber is not realistic. We need to go to other methods."

Monitoring Oxygen, Co2 levels

The pilot oxygen and CO2 level indicator system that Wright referred to is currently under development at the USAFSAM Department of Aeromedical Research. He said that the system will feature mask-mounted sensors that would provide a color-coded alert to pilots that would warn them when the concentrations of O2 and CO2 in their breathing mask air supply were at safe, intermediate or dangerous levels. These sensors would also be located in the cockpit. Initial testing of these sensor systems is scheduled to begin this summer, Mayes said. Preliminary plans are to place these sensors in test jets next year.

"We will have a number of larger efforts going on once the mask sensors are validated to look at the work of breathing in different aircrew environments," Mayes stated. “We also have been studying the effects of workup breathing in different configurations of air groups like the F-16. We don't really have much baseline knowledge for how much is too much for workup breathing in an airspace environment."

The mask and cockpit sensors will also provide a means for measuring pilot breathing under G-loading, Mayes added. In one project, data from the mask sensors will enable the USAFSAM research personnel to look at the metabolic cost of a simulated aerial combat maneuver in a centrifuge. In the first phases of this research, pilots will be experiencing from five to nine Gs and back and forth, with their breathing work being measured while they perform the anti-g straining maneuver (AGSM). Later, Mayes hopes that such tests can be conducted in actual aircraft environments.

Testing of the sensor systems in actual aircraft is important, because the goal is to implement them in operational aircraft. Currently the USAFSAM research team is asking the Air Force Test Pilot School at Edwards Air Force Base if they will allow the sensors to be put into the School's F-16s and have pilots perform actual sorties with the equipment aboard.

G- training

One of the casualties of Department of Defense budget cutbacks is that the Air Force has been forced to cut back on the amount of flight time service pilots can log. Although all fighter aircrew must undergo G-training in a centrifuge to learn and practice the AGSM, less flight time can keep them from retaining their AGSM training. Improper practice of breathing techniques that make up the AGSM under g-loading can lead to less oxygen reaching the brain, causing loss of visual acuity, disorientation and possibly G-force-induced Loss Of Consciousness (G-LOC). This is a major reason why USAFSAM medical personnel want to further study and document aircrew breathing and absorption levels of oxygen and CO2.

" As far as G-training, you need to be current, " Wright said. "It is very expensive to fly airplanes like the F-22. The problem is that pilots are just not flying very often. What these guys need is more currency. If we have to take them up in a T-38 to practice some of these techniques, then that might be a part of the solution, because practicing an anti-g maneuver on the ground or in the simulator just is not realistic. They need to fly, and they also need oversight presumably with the flight surgeon or squadron mate. There are a lot of ways this is being addressed, but I think that we are at a point in our Air Force when we are allowing pilots not to fly because it is too expensive. So we have to find a way to address that."

While one other option might be to have aircrews take recurrent g-training in a centrifuge, according to USAFSAM's Dr. William "Buck" Dodson, with only one currently available it would be is problematic to get pilots to it on a regular basis. So he does not feel that this training option is one that has the most feasibility. That centrifuge is located at Brooks City-Base in San Antonio, TX. ETC is currently installing an ATFS-400 Model 31 high- performance centrifuge at the new 711th Human Performance Wing complex at Wright- Patterson, but that system is still under development.

Cognitive Testing

Since a reduction of oxygen to the brain under g-stress can affect aircrew cognition, the USAFSAM Department of Aeromedical Research has started to look into ways to test cognitive states of pilots in operational environments, according to Dr. Dan Van Syoc, Deputy Chief of the Aeromedical Consultation Service at USAFSAM. The question is how to find out if aircrew members are making good decisions under operational conditions, since currently cognitive testing can only be done in an office setting, he pointed out. At this point, there is no way to test cognition in the aviation environment and pilots are not interested in wearing some of the equipment that would monitor and support cognitive testing, but this may be possible in the near future, Van Syoc said.

Other research

While the Department of Aeromedical Research conducts an extensive number of studies related to high- performance aircraft environments, its personnel are involved in a number of other areas of that are focused on human performance and resultant aircrew safety that look at such factors as aircrew fatigue. Van Syoc said that several studies are being conducted concerning Remotely Piloted Aircraft (RPA) operators who may be suffering from post-traumatic stress disorder (PTSD) and similar conditions as the Air Force places more emphasis on the deployment of unmanned aircraft. Another area is improving the performance of medical personnel serving on aeromedical evacuation aircraft.

 

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ETC is currently installing an ATFS-400 Model 21 high-performance centrifuge at the new 711th Human Performance Wing complex at Wright-Patterson. Image credit: Environmental Tectonics Corporation.

"What we do in human performance sometimes also gives us a payoff in safety as well, for example on the issue of fatigue," Dodson said. "With less fatigue, performance will be higher and at the same time safety-wise aircrews also will be less likely to be involved in a mishap incident. And if we can optimize the physician's medical judgment during those aeromedical flights, we are helping him directly and the patients indirectly if we want the best outcomes."

The USAFSAM is an internationally renowned center for aerospace medical learning, consultation, aerospace medical investigations and aircrew health assessments. For more information on USAFSAM research, go to www.wpafb.af.mil/afrl/711HPW/usafsam.asp


NASTAR Center

Several recent and future aeromedical research programs at ETC's National Aerospace Training and Research (NASTAR) Center could well help the US Air Force in its constant efforts to improve aircrew performance and safety, as well as training, according to NASTAR Research Scientist Mike Newman. For example, a just-completed study for MIT conducted in the Center's centrifuge investigated how hypergravity changes pilots’ perception of their orientation, such as when banking their aircraft at different angles under various G-levels, Newman explained. While the study for MIT was geared to crews in long-duration space flights, the work relates to how long it takes train aircrews at various G-levels, he said.

Another research effort Newman cited is a just- begun project for Drexel University that focuses on monitoring pilot cognitive performance while under G-loading in the Center's 400 centrifuge. Pilots in the centrifuge will be wearing multiple body function sensors, including those that employ near-infrared spectroscopy to measure blood flow in the prefrontal cortex, the front of the brain, Newman explained. The goal is to see how the stress of g-forces changes pilots' performance of specific memory tasks in order to get an idea of pilot cognitive impairment under g-loading.

In an in-house study, ETC is looking at how pilots move their heads in various types of maneuvering and training environments, namely in non-motion and motion flight simulators, as well as ETC's ATFS-400 Model 31 high- performance centrifuge and in actual aircraft flight. What the company is interested in is how pilots change their behavior based on their training environment.

"We want to see if pilots who are training in a non-motion environment are moving their heads around much more than they would than they would if they were actually in an airplane," Newman said. "This relates to problems with head-mounted displays (HMDs) in flight helmets. So we can extrapolate that to the HMD problem and see how big an issue that would be, based on how these parameters change in the training environments."

" People assume that pilots move their heads the same way in the non-motion environment, but there is actually no data to prove that," Newman continued. "We want to quantify these movements, because we have had a lot of pushback that training in certain simulation environments alters the way pilots move their heads, and that this is going to translate to a degradation of training or a bad transfer of training."

This work will also relate to an F-35 Joint Strike Fighter (JSF) pilot helmet research project that ETC Business Development Manager Ken Ginader has proposed to the Air Force. Although pilot workload and efficiency will potentially be enhanced with the use of HMDs, they might affect helmet weight and center of gravity, and the effect of wearing heavier helmets during long-duration missions are not fully understood.

The added helmet weight could impose muscle fatigue and discomfort that might lead to pilot distraction, particularly under G-loading, Ginader speculated. He proposes a that a pilot-in-the-loop, modern ground-based static and dynamic flight simulation technology- based research project will yield a comprehensive assessment of pilot endurance and physiological effects with a HMD-equipped helmet in an operationally realistic environment. – Chuck Weirauch