Question:
Might have been, but here is what happens with leg straps that are too tight. On opening, blood is 'sloshed' to the lower extremities. Blood return from the legs is relatively poor and the leg straps act like a tourniquet (diminishing venous return to the core without directly impeding arterial flow) and 'captures' or 'pools' blood in the legs that cannot now be used for things like perfusing the brain. Contrary to popular belief, return of blood from the lower extremeties is not primarily due to the pumping action of the heart (while in a more or less upright position) but from muscle contraction of the legs. If you dissect one of the large veins in the leg you will see a series of 'pouches' in the vein wall, with the open end toward the torso. Each time you contract your lower leg muscles, you force the blood upward. When the muscles relax, the blood falls back into the pouches until the next muscle contraction, when it is squeezed higher. This is one of the reasons you see varicose veins in people who have jobs where they spend a lot of time standing (not walking) and women who wear high heals (it's also a big reason for their upper thighs and asses turn to flab, but's that another subject). Not having regular muscle contraction to promote return, the blood 'pools' in the pouches which loose their elasticity over the years and start to bag out resulting in varicose veins and clot formation. So what does all this have to do with skydiving??? In addition to properly fitting leg straps, you can help promote blood return (and thereby help to stay conscious) by strongly contracting your leg muscles several times in about 1-2 second intervals.

Answer: -I've had it happen myself under canopy as a student (although I never actually passed out). the vagal response is a natural mechanism that the body uses to counteract the adrenaline surge after a scare/excitement is over. The heart rate slows; the blood pressure drops; people often feel nauseated, lightheaded; they feel tingly in their toes, hands, and mouth. Some people get a rushing sound in their ears. Then they may or may not pass out. The temporary loss of vision is from lack of blood to the optic nerve (and the brain--which is why you pass out). This is not really a ophthalmic migraine which is caused by spasm of arteries. Loosening the leg straps would help some since that's where blood pools when the blood pressure drops, but the real issue is how excited/nervous a person is before and during the jump versus how prone they are to a vagal response. Some people in my medical school class used to pass out watching blood get drawn. But they all got over it. They just had to calm down a little. -As a paramedic for 16 years and a tandem master for 6 years. I can tell you that most of the black outs you see involving students, doesn't have to do with the harness. It's a medical problem called "psychogenic shock". It's defined as: a fainting spell as a result of transient generalized vasodilatation in response to a sudden emotional stimulus. They are fainting to do the fact that all their major blood vessels are dilating causing the blood to rush away from their brains to the legs and trunk. I have seen it caused by a sudden sharp pain, but not the dull throbbing discomfort of the harness. Some symptoms that you may or may not be seen are: cool and clammy skin, sweating. nausea or vomiting. From my experience you can expect no cooperation from your student so get ready to protect him and once you land get his feet and legs elevated. Keep the student lying down until qualified medical help arrives.