How Pilots Prepare for High G-Force Flights

• Air Force pilots receive extensive training to avoid loss of consciousness during high-acceleration flights.
• The Anti-G restraint maneuver helps pilots remain conscious while flying.
• Technologies such as the Automatic Ground Collision Avoidance System have reduced G-LOC accidents.

You are flying a fighter plane and you are accelerating. But you’re relaxed – a little too relaxed. Suddenly you notice your peripheral vision starting to fade. In a few seconds, you lose consciousness completely.

This is G-LOC, or G-induced unconsciousness, and the results can be catastrophic.

In flight, levels of acceleration called G-force vary, and when pilots experience their highest levels, the pressure of gravity pushes blood toward the lower half of the human body, causing poor blood flow to the upper half of the body. body.

“When this happens for a long enough period of time, you will lose consciousness,” Lt. Col. Carolyn Price Moore, an aerospace physiologist and chief of the 19th Air Force’s aircrew performance branch, told Business Insider .

Air Force pilots must prepare their bodies to respond to the highest levels of acceleration during their flights. Experts explained how pilots manage to overcome these efforts under high pressure.

“All the training we do is to make sure the pilot is capable of performing the maneuver,” Price Moore said.

The Anti-G Straining Maneuver, also known as AGSM, is an exercise that pilots use during high levels of G-force to prevent G-LOC.

Air Force pilots learn about G-forces, AGSM, and all the ways increased altitude and pressure can affect the body in their first week of classroom training.

Learn the basics

When pilots start, their introduction to the G-force is done gradually. This gives them time to develop the fitness needed to withstand pull-ups on the Gs.

“You really want your lower body to be very strong, so if you can do exercises that improve your lower body strength, that will go a long way in improving G tolerance,” Price Moore said.

Athletes tend to have an advantage when it comes to preparing for high G-force flights because they may already have significant lower body strength. Although size is out of the pilot’s control, it is also helpful to have a small size because blood can flow through the body more quickly.

Students undergo introductory primary acceleration training where they are individually spun through a human centrifuge that gradually increases in G.

“It’s a gentle, slow climb to the G realm that allows them to get used to the feel of the centrifuge,” said Senior Master Sgt. Tyler Long, who oversaw the training and performance facilities.

He called training a “roller coaster on steroids,” saying “it’s a feeling you’ve never felt before in your life.”

Students wear anti-G suits that act as an external “air bladder,” hugging the lower body to promote blood circulation if a student does not have enough lower body strength to flex on their own.

The training also includes what Long describes as the Sakhalin profile, a simulation in which the student must follow an aircraft on screen as it experiences and overcomes varying levels of G-force.

“The whole point is mastery. Get them to master that G force, get them comfortable to a point where they can now fly an airplane with a higher G capacity,” he said. -he declares.

New Air Force pilots typically began flying a T-1 Jayhawk trainer aircraft, but that aircraft is being retired for undergraduate pilot training and has been replaced with a principles simulator fundamentals of air mobility. The student will use this simulator for several months.

An undergraduate pilot will then move on to flying a T-6 Texan II aircraft within approximately seven months as part of undergraduate pilot training and will progress to either mobility or heavy aircraft training at using the AMF simulator, or training on fighters and bombers in a T-38 Talon aircraft. . Students are assigned an aircraft at the end of the UPT.

Once the student has mastered this training, they will fly their assigned aircraft and master it during the formal training unit.

Dealing with the real thing

The two main mechanisms of AGSM that prevent a pilot from passing out are calculated breathing and lower body compression. It’s a simple but life-saving maneuver.

Before the pilot even enters the onset of G-force during flight, he must flex his lower body, such as his glutes, hamstrings, and other muscles, as tight as possible.

“They tighten and hold and it compresses all of the blood vessels, all of your veins and arteries in the lower half of your body to help prevent that buildup,” Price Moore said, explaining that flexing allows blood to pool. . to stay and continue to circulate the upper body.

The most difficult step is performing the proper breathing technique. This allows blood flow to return to the heart and then to the brain.

A pilot must take a big deep breath, holding the air in his glottis, located in the throat, before the onset of G or acceleration occurs, then begin “air exchange.”

Air exchange is a rapid release of air that should occur every three seconds. “It’s not normal breathing, it’s a forced air exchange where you’re basically forcing the glottis to open and close very, very quickly,” Price Moore described.

The sound of air exchange sounds harsh, like a cross between panting and coughing.

In training, all this is done under the supervision of the instructor who accompanies the student on the plane. They must listen to air exchanges to ensure and approve if the pilot is breathing correctly.

Accidents still happen

Sometimes G-induced loss of consciousness cannot be avoided and a pilot may also experience symptoms such as brief amnesia, nausea, disorientation and confusion, as well as neck and back injuries.

Flight accidents have also occurred as a result of pilots fainting. For example, among other incidents, the Navy Blue Angels and Air Force Thunderbirds lost demonstration pilots to G-LOC. But many military aircraft are now equipped with an automatic ground collision avoidance system that helps prevent accidents.

“When automatic GCAS is activated, the aircraft itself receives messages if it is essentially too close to the ground, and if so, the aircraft itself will take over and do what is required. calls it a ‘flight up,’ and we’ll fly the plane back to a safe altitude,” Price Moore explained.

“Since the installation of automatic GCAS, we have had far fewer incidents of unconsciousness or G-induced accidents,” she said, adding that “operationally, automatic GCAS has kind of changed the game in terms of G-LOC.” accidents, so there is this safeguard. »

But even with some sort of safety net on the plane, that doesn’t make it any less necessary for U.S. military pilots to train as if they don’t and prepare their bodies for the intense, high-pressure challenges of the high speed flight.