Battling G forces at Holloman Air Force Base

Pretty much anyone in the aviation game knows of the United States Air Force bases Nellis and Eglin for lots of reasons – they are massive operations, getting routine attention for their activities including Red Flag, Area 51, and the missile and electronic warfare ranges along the Florida panhandle. As a matter of fact, most commercial, general aviation, and passenger flyers have had their routes in the western and southeastern United States dictated to avoid military restricted and training airspace for better or worse.

There is another Air Force base not having the notoriety of those mentioned above – Holloman AFB, in the southeastern corner of New Mexico. Holloman’s history dates back to its establishment as the Alamogordo Army Field in 1942 and continued on to its current status as Holloman Air Force Base. Along the way, it has served as weapons development establishment – about ninety miles south of the Trinity site where the first atom bomb was detonated, a test base for early versions of ballistic missiles, training for Air Force and Allied aircrews, a stateside station for German Air Force units, and an alternate landing site for the Space Shuttle.

Holloman also housed a primate research center whose residents contributed in no small way to America’s manned space flight program. Some say the primates often ventured to the officers’ club for refreshments and adult beverages – they tipped well, were good at a broad variety of bar games, and blended in well with the fighter pilots of the 49th Fighter Wing on many Friday night happy hours.

F-117s at Holloman
Over the years, Holloman has hosted some unique airplanes.

Over Holloman’s 75-year history, almost every Air Force and many Army aircraft spent time operating in the airspace in and around Holloman – B-24s, B-29s, drones, AH-1s, UH-1s, F-100s, F-4s, F-15s, F-117s, AT-38s, F-16s, and F-22s have used the White Sands Missile Range airspace for training. Drones for use as targets have operated there for years: F-86s. F-100, F-106 and F-4s gave it their all to validate new weapon, radars, and aircrew training.

Today the MQ-9 Reapers are based at Holloman and part of the UAV force so prominent in military operations – worldwide. Holloman also has some unique facilities for testing radar, signature, and weapons. Col John Stapp took a ride on a rocket-powered sled that gave him the title of world’s fastest man on earth for many years. The famous bunker buster weapon based on an artillery barrel made its bones on one of the Holloman test tracks, along with a “vehicle” achieving over Mach 8 on a sled not so long ago.

The ranges around Holloman are fantastic assets for flying training. There is an air-to-ground range within ten minutes’ flying time. Taking off to the west, you can make a sharp right turn and enter White Sands Missile Range (WSMR) supersonic airspace in less than three minutes from brake release. If, for some reason, that space is not available, there are several other operating areas north and east of Holloman useful for tactical training, but sometimes cause airline traffic to deviate around active military training. Inconveniences for passengers and general aviation, but in most cases there is not routine encroachment on civilian operations.

There was another facility at Holloman important for Air Force training and operations starting in the late 1970s. That was the centrifuge, a device used to expose Air Force pilots to the high G performance of the F-15 Eagle and F-16 Fighting Falcon (aka the Viper and Lawn Dart).

Unlike earlier fighters, the Eagles and Falcons could attain and sustain high G loading. Both were capable of attaining nine Gs and could, under certain conditions, sustain these high levels for several seconds. This capability had advantages in aerial combat and in performing defensive maneuvers against air to air missiles. The downside was on many occasions the G performance of the jets could outperform the capability of the pilots, even with the old school G-suits, causing G-lock and the pilots to black out out and in some cases lose control and crash. The centrifuge was installed at Holloman to provide a safe, controlled environment to experience high G for several seconds and aid developing techniques to reduce the chance of G-lock.

I’ll come back to the centrifuge later, but for now I want to talk about a personal experience with G at Holloman. There is good weather in New Mexico, four seasons’ worth, so much that our F-16 colleagues at Hill AFB in Utah would come visit us in the winter to enjoy our not-so-cold, mostly clear weather. These visits took place over a three-month period, when they’d send a squadron down for Dissimilar Air Combat (DACT) with the Eagles and AT-38 Talons on our air patch. This was a great opportunity for all involved, and we looked forward to having Vipers as guests.

F-15s in flight
With plenty of airspace around, there are plenty of good dogfights at Holloman.

I remember two specific missions, one a one v one with a Viper driver I’d introduced into the fighter business while an instructor pilot at George Air Force Base back in the early 60s. Some 15 years later we were seasoned officers and pilots and had the chance to use our jets and skill in aerial combat. It was a treat!

Both our jets were clean, mine an F-15A “sport model,” his a late Block F-16A Lawn Dart. Both had AIM-9 all-aspect missiles and internal 20mm cannons. His advantage in size (small) was mostly offset by the setups we used – all within visual range. We took off together, me leading, him ten seconds in trail, turning right into WSMR, cleared supersonic less than five minutes after brake release. We climbed up in to the mid-twenties, did our proforma checks of fuel, flight controls and did some G-tolerance turns to check our personal readiness for some hard performance. Good to go – fight’s on!

Flying clean, we had fuel for about four or five engagements, starting with some short-range setups allowing practice of the offensive and defensive techniques for employing and defending against IR guided Sidewinders (or their Soviet analogs). Then our last engagement was a guns-only exercise to test how each of us could manage our own aircraft against a different breed – DACT. The setup is simple: start line-abreast, turn away and after an honest (but there is a fact of, “if you’re not cheating, you’re not trying” – just kidding) count for separating, turn-in and go for guns.

It was a good fight, lots of moves and counter-moves, going up and down with scissors on occasions, until we were nose down with about 2,000 feet of separation, both going for the other’s six o’clock.

At this point we were both light, with lots of thrust and G available. Descending, it is easy to generate and sustain 8G+. We were approaching the floor – and I was working hard. I needed to take a breath; it was getting pretty gray with sustained G. I let it out and all of a sudden, I felt like I had an elephant on my chest, and he had no intention of letting me take a breath. It felt like I was having a heart attack! We were at the floor, so we had a mutual knock-it-off and I felt a great relief. We rejoined, climbed out and headed for home. Uneventful RTB and debrief, a good workout and good mission for both the Eagle driver and his Viper companion – but what the hell happened to me? A trip to the “fuge” was in order, one because it was scheduled, and two for some answers.

The explanation of what happened is simple – under high G, if you let your breath out, most of us don’t have the strength to reinflate our lungs. You are out of air, until you back off the G and can take a deep breath. It isn’t GLOC – that’s when your heart can’t pump enough blood and your eyes are quickly going out of business. This usually starts with a grayout and eventually, if the G is not relaxed, a blackout and unconsciousness. Usually your lights are only out for a brief time, but a severe GLOC can last for long enough for real trouble to develop and if you’re in a deep dive, or close to the ground, a fatal crash.

This is where the centrifuge comes in. It is operated by trained professionals and supervised by medical professionals, usually a flight surgeon. The centrifuge is a pod roughly representing a cockpit environment, on a long arm connected to a hub and the machinery that can rotated the device at a variety of speeds creating a controlled, variable G environment. This allows a rider to experience sustained G up to and including loading nine times the force of gravity, or the G-loading capability of modern fighters, including the Eagle and Viper.

Centrifuge
The centrifuge at Holloman was not an amusement park ride.

A fuge ride only lasts a few minutes, but allows the subject to see the extreme G environment and practice the techniques for preparing for it and developing the capability of handling 8 or 9 Gs for the several seconds experienced in a close-in dogfight or last-ditch maneuver to avoid an inbound missile. Much of it is in anticipation and controlling breathing with muscle tensing and discipline. The subject of the fuge ride is filmed so he (and his “fans”) can observe the effects of G, in most cases the eventual nap and rapid recovery when the rotation is slowed down and G relaxes. This film is often characterized as a view of self at advancing age – eyes drooped and jowls taking on a hound-dog look. I have my ride on a CD. I’ve never looked at it!

There is some technology helping to combat G – the classic G-suit chaps introduced toward the end of World War II. The chaps are attached to the aircraft by hose, and inflate around the legs and abdomen to keep blood (and its oxygen) from pooling in the lower part of the body and avoiding GLOC and blackout. The F-16 has its ejection seat inclined to reduce the workload of the heart pumping blood upstream. There is also a vest that is sometimes used and performs the same function. These are all good things, but the experience of the fuge is invaluable in allowing aircrew to experience the GLOC phenomena and cueing them to the onset signs during hard maneuvering flight. A fairly recent technology is the application of G and attitude sensor on the aircraft, particularly the F-16 that, when sensing high in proximity to the ground will automatically take of the controls and make corrective inputs to avoid collision with the ground.

So, in short, newer aircraft, with great aerodynamics, responsive, powerful flight controls and engines with extremely fast response and high thrust took pilots into a regime much different than available on the Century series and comparable foreign fighters – this was an overwhelming increase in performance and capability, but brought hazards in the same bag. Training, physical conditioning and the addition of the centrifuge experience, along with technology developed by engineers and human factors experts have significantly reduced the hazards of GLOC, allowing US fighter crews to exploit performance capabilities in air to air and air to ground phases of combat. Net result: safer flying and and impressive combat results! All good.

As I alluded earlier, there’s another Holloman-Hill story out there – for another day.

3 Comments

  • Holloman was a great assignment. Only regret we didn’t get to participate in Desert Storm. Not the other guys made us all prout. Hope all is well with you!

  • Holloman was a great assignment. Only regret we didn’t get to participate in Desert Storm. But the other guys made us all proud. Hope all is well with you!

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