Avoiding the dreaded G-LOC. Chuck Weirauch reports on the new US Air Force centrifuge at Wright-Patt.

The US Air Force’s newest and only human-rated centrifuge is now providing all initial and advanced high-G acceleration training for the Service’s jet fighter pilots, replacing all previous facilities, such as the one at Brooks City Air Force in Texas. Located at the 711th Human Performance Wing’s School of Aerospace Medicine at Wright-Patterson AFB in Dayton, Ohio, the 9G-capable centrifuge features a 31-foot-long, 30,000-pound swing arm. Student pilots ride in one of three egg-shaped cockpit modules attached to the arm that spins up to 45 mph during “flight.”

US Air Force School of Aerospace Medicine operational physiology technicians prepare to climb into the training centrifuge at Wright-Patterson Air Force Base. Image credit: USAF/Michelle Gigante.

Two of the cockpits are reconfigurable to match the aircraft the students fly in during training at their flight schools, while the third is employed for aerospace medical research. All three feature a high-resolution, semi-panoramic, 210-degree horizontal by 110-degree vertical field of view display to provide a more realistic simulated training environment for the students. Another key feature that increases realism is the capability to control the G-point vectoring – the pitch and roll of the cockpit modules – so that they can more closely replicate aircraft attitude during flight. Yet another feature that improves realism is the ability to network the three modules and the centrifuge control room together to simulate a battlespace environment – similar to those provided in a Distributed Mission Operations (DMO) environment where the Air Force links multiple flight simulators for networked training exercises.

Growing Student Throughput

The new facility began operations on 1 October 2018, and took over training from Brooks City AFB as of January; it has provided acceleration training for more than 300 students from Air Force bases across the US. The goal is to qualify up to 1,200 student pilots each of the next five years.

The students come from a variety of communities, explained Flight Commander and Training Manager Air Force Captain Adam Lohn, all with the need to obtain a G-rating before they can advance in their flight training programs. Typically, those that require initial acceleration training – up to 7.5Gs – are those pilots transitioning from T6 primary trainers to T38 jet aircraft. Those that require advanced acceleration training – up to 9Gs – are progressing to more high-performance jet fighters, such as the F15 C and D models, the F16, F22 and F35. One of the cockpit modules is configured for the F16 only, while another can be reconfigured to replicate the cockpit of any of the other jet fighter aircraft at an unclassified level.

Straining Training

The goal for the students is to master the physical Anti-G Straining Maneuver (AGSM) critical for them to avoid the dreaded G-induced loss of consciousness (G-LOC) condition, which can cause pilots to black out and possibly lose control of the aircraft. And master it they must in order to achieve their required G-qualifications. According to Lohn, how long it takes for pilots to achieve their goal depends on how many days – up to three, or a maximum of 72 hours – it takes them to learn the technique and demonstrate that they have indeed mastered it. Most (96 percent) satisfactorily complete their training by the first day.

To do so they must convince Lohn, an aerospace physiologist who observes the students in the cockpit module from the centrifuge control room during their “flight,” that they have employed the AGSM properly a number of times during the training session. Although the students are taught the AGSM early on in their initial flight curricula, it is quite another thing to demonstrate it properly in a sustained high-G environment. Their first exposure is at Wright-Patt during their first seven days of initial training, but this is not as thorough as the real test they will undergo during the high-G training course in the centrifuge.

“During training, we do not medically monitor students in any way at all,” Lohn explained. “We just monitor them in person as a physiologist and as a medical observer for safety. What I am looking for when the students are spinning is a light-loss test – in other words, the level of light vision lost because of not maintaining proper blood pressure at the cranial level while attempting to perform the AGSM. I am also looking to see if they executed the mechanics of the AGSM properly. They are measured on a Pass-Fail scale, which is determined on how they perform the AGSM.”

In addition to providing improved acceleration training overall by increasing realism with the new centrifuge, the combination of the G-vectoring capability and the semi-panoramic display also help to reduce the number of motion sickness cases among the students by reducing vestibular disturbances that can lead to such sickness, “something that is huge,” Lohn added. These capabilities will also allow the School of Aerospace Medicine physiologists to begin conducting negative-G research, which they have not been able to do with previous centrifuge systems.

Researching Unexplained Events

School of Aerospace Medicine Program Manager Scott Fleming outlined additional research that the physiologists hope to conduct in the research cockpit module in addition to the negative-G investigations. These include looking into unexplained physiological events that have taken place in operational aircraft in the recent past, including oxygen-deprivation problems across several types of Air Force and Navy jet fighters.

Of course, any potential solutions to such problems must be tested in helmets, masks and sometimes G-suits in a high-G environment. Fleming explained that the Navy does not have its own centrifuge, so the Wright-Patterson AFB School of Aerospace Medicine is conducting high-G research for the Navy, particularly for the Naval Air System Command (NAVAIR).

“Anytime that we make a modification to these systems that are involved, they need to bring them back to the centrifuge and revalidate that the system will function properly in that high-G environment,” Fleming explained.

Originally published in Issue 2, 2019 of MS&T Magazine.