I don't want to clog up this thread with comments from someone who isn't even in the aviation industry but I'd like to clarify a couple of points.
One post states that there's a difference between "a drinking problem" and "alcoholism". After almost a quarter century of interest in this subject I'd have to say that this is a meaningless distinction. Whichever label is chosen the phenomenon's the same. It could be said that the only really useful definition of "alcoholism" is one which is applied to an alcoholic by himself.
As for the notion that for people who have a serious compulsion to drink (avoiding for the moment the labels mentioned previously) it's quite possible to revert to "normal" drinking, I'd say that this is not borne out by either my own experience or by the evidence from studies I've read. Which is not to say that it's unknown. As best I recall, in the Harvard study there is evidence that amongst a blue-collar set of the sample there is evidence of this reversion where, after getting married and "settling down", some individuals who, during adolescence and early adulthood, had previously met the DSM criteria for alcoholism no longer did so.
But it looks more likely that after a sustained period of heavy alcohol use, whether episodic or regular, the behaviour pattern becomes "hard wired". Which is something alcoholism has in common with other behavioural disorders. Personally I'd rather like a glass of decent claret occasionally but the risk/reward ratio, having seen many people crash and burn after engaging in similar experiments, is unacceptable. Abstinence appears to be the only reliable solution.
Many "high-functioning" alcoholics may never be found drunk on the job for decades - or ever. Unfortunately the damage to emotional responses done by habitual drinking becomes significant long before intellectual or physical symptoms appear. This alone can significantly erode decision-making processes.
For anyone concerned about their own relationship with alcohol (or drugs for that matter) there are a number of questionnaires published which enable a rough evaluation. Here's one:
Alcohol Self Test | 20 Questions | 20 Question Alcohol Self Test | Alcohol self-test | Alcoholic Test | 20 Questions | AA
This derives from the 12-step AA movement which not everyone can stomach but it's useful. There are several others, essentially similar, widely available online. One thing I'm quite certain about is that having done these questionnaires at the beginning of their recovery and scored high enough to qualify, every alcoholic I know scored far higher when repeating the test a couple of years into sobriety - myself included! Denial is often the litmus test of alcoholism.