Dr. G and the G forces

By Dr. Sanjay Gupta Chief Medical Correspondent

I had one of the most thrilling rides of my life yesterday. I was invited by the Blue Angels to ride along on an $18 million jet for about 90 minutes, flying out of Naval Air Facility El Centro, California. I approach these stories like I approach a med school exam. I studied really hard, and tried to learn everything I could about the physiology of pilots.As is often the case, though, there is a big difference between reading about something and doing it.

Now, in full disclosure, I was very worried about taking this ride. I do get sick in the back of cars, and even a little movement on a boat makes me want to toss my cookies. Things like Dramamine have worked in the past, as has ginger. They do not work, however, when you are traveling at supersonic speed in a high-performance jet. The combination of barrel rolls, quick and violent turns and super high G forces - the force of acceleration or gravity that feels like extreme pressure on your body - is not easily treated with any kind of medication.

Before the ride, the Blue Angels gave me an outstanding briefing on anything and everything about the plane. It has two engines that can each generate 16,000 pounds of thrust - and they did. It can travel 1,200 miles an hour and go as slow as 120 mph. The pilot explained to me that going slow was what made this plane unique. Any plane can go fast, but to be able to "hit the brakes" and suddenly slow down made this F18 Hornet, a special plane. It can fly inverted for quite some time, and I didn't even know planes could really do that. There also was plenty of discussion about a "bonus ride." Yep, that's the ejection seat and it can rocket you high enough in the air that even if you are ejected from the ground, you would land safely with a parachute.There is no question that it was cool to break the sound barrier, though I didn't hear much when I did. We turned cartwheels in the sky and flew through canyons like I was playing a video game. I learned breathing techniques and exercises that help one combat G forces.

Simply tensing your leg muscles and trying to stand up against the 12 point harness will force blood into the upper part of your body, including your heart and brain. Contracting your stomach muscles and saying "hick" loudly also does a good job of keeping that blood where it needs to be. From a medical standpoint, at 4G's, you will start to lose color vision, which is why it is called "graying out"; 4.5 G's and you may lose vision all together. Higher G's and your lungs start to collapse, your esophagus stretches, your stomach drops and blood pools significantly in your legs. It's hard for the human body to take, although my pilot seemed to be enjoying it and joking the whole time, sometimes at my expense.During my flight, I topped 6 G's - six times the force of gravity. The exercise and breathing techniques that I used in training worked for the most part - except for the one time I think I passed out, only to have Lt. Frank Weisser say,

"Hey doc, you awake?" I thought I was. I wasn't. And, yes I completed both P's of my Blue Angel flight. Not only did I Pass out, I did Puke. I guess burritos weren't such a good idea for breakfast.It was a once-in-a-lifetime experience, and I think I will keep it that way.

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