As economists like to say, the only constant is change, and that applies equally to aviation and to medicine, particularly aerospace medicine, which is the specialty practiced within the FAA flight surgeon's offices.

On the aviation side, one big change is that large aircraft are now capable of endurance that exceeds the upper limit of the maximum duty day. Fatigue and sleep adaptation are therefore issues for all air crew members in both the cockpit and the cabin. On the medical side, the extension of retirement to age 65 for airline pilots and a related revision to extend the valid terms for medical certificates for those under age 40, which affects all pilots, derived from growing awareness in the greater medical community that opinion on age-related effects on performance had changed. And the reason it changed was based on hard evidence that people don't "age" the way they used to. A Stanford University study published in August found, for example, that taking such a simple measure as exercising daily delayed aging markedly. Pilots, as a rule, are generally even more attuned to fitness needs than the rest of the population, so when the changes came, there were many who wondered why it took the stethoscopers so long.

Another big change in aviation medical matters that's gotten less notice is a result of the proliferation of data-mining initiatives within the government since 2001. It's not as if it wasn't a growing phenomenon before that: Marketers have promoted "discount" cards that exact a price for that eight cents off your 13-ounce can of coffee - their computers gobble up information about what you bought and how you paid for it. Register for a warranty on your new power drill and Acme Power Tools wants to know how many cats you own. Every data point is valuable to someone.

Recent scrutiny of airmen certification standards by the NTSB and others has led to a strong suspicion that a large number of pilots were trying to obtain a disability status under one wing of the government and then forgetting all about that same "impairment" when reporting to the FAA. Maybe there was a time when it would have taken an army of file clerks to find the evidence of such malfeasance, and people could have gotten away with it, but that time is gone. Information today is exchanged on a large scale, and both disabilities and evidence of alcohol or substance abuse are now easily accessible to the FAA.

If you think, "Nah, they'll never find out," think about this: Federal, state and local databases containing disability information as well as the national driver registry containing data on everyone packing a driver's license along with their driving records - that means arrests, not just convictions - can land, figuratively speaking, on the FAA flight surgeon's desk. While you're reading this, vast computer networks are reading all of that and matching names, Social Security numbers and whether an individual claims vision impairment.

There's more than one way to lose your medical certificate, according to Dr. Michael A. Berry, manager for medical specialties at FAA headquarters in Washington, D.C. The quickest and most direct way used to be to have a heart attack, he says. "There was a time when a heart attack or heart bypass surgery [in which blood is rerouted around blocked coronary arteries or the arteries are removed and replaced by healthy tissue] disqualified you. Now angioplasty [unblocking the coronary arteries by widening them using a tiny balloon] is accepted and for all three classes of certificates." You can even obtain a certificate after a heart transplant, Berry says.

He points out that there was a time when hypertension - high blood pressure - was disqualifying unless you treated it only with diuretics, or water pills. "Today, you can take just about anything," he says, including various blockers. While cardiovascular issues still dominate in matters of airman certification, the proliferation of drugs for almost any conceivable malady or symptom moves medication up the list of concerns for both Berry and the population of certificate holders whose fate he holds in his hands. "Medication is everywhere," he says, "and we just wish pilots would consult with us before taking it."

In a recent case, Chantix, a brand of varenicline, which helped people quit smoking, was approved for use after it had been on the market for a year and with no marked side effects. "It looked OK," Berry recalls. The drug had proven in tests to help more people to quit than Zyban, another stop-smoking prescription aid, and it was between two and three times more effective than a placebo, or sugar pill. Then reports began surfacing in the medical literature and the press about a side effect in people prone to depression or agitation. The Veterans Administration, which had been prescribing it for patients who smoked and suffered from post-traumatic stress syndrome, reported that some patients had been having thoughts of suicide while taking Chantix.

"We did a 180-degree reversal," Berry says. "At first there seemed to be no adverse side effects, but as the experience with it increased, that proved not to be the case. We won't consider anything that's been on the market for less than a year. But maybe a year isn't enough."

The issues of sleep and fatigue are hot buttons lately, he concedes. "We're currently looking at the whole issue of pilot fatigue and use of sleep aids and trying to come up with solutions that are safe and reasonable."