I don't think an accident ever occurred because of smoking in the cabin? (Possibly one because of smoking in the lavatory, and I'm not even sure).
For smokers, going 4, 6 or 9 hours without smoking is just unthinkable; I know it was for me. So glad I quit (a very long time ago), but I don't know how smokers deal with it today.
There are plenty of reasons why people shouldn't be flying planes. Being unable to not smoke is not really any different from being unable to resist getting drunk or falling asleep, as far as safety people have to be concerned. It fundamentally doesn't matter if it's "your fault" or "addiction" or a "medical reason"...
I quit smoking the old-fashioned way so I don't have a first-hand experience in that matter, but I was thinking a lot about this once. I belive patches and gums may not work in every instance. Please let me provide some context.
I was smoking for around 7 years, from my late teens (jus a couple smokes per day) to my early 20' (1.5–2 packs per day). I haven't smoked in quite a few years, I think it's close to 10 years, I don't count anymore.
I have never felt addicted to nicotine. To cigarettes, yes. I was addicted to all those little smoking rituals, gestures, and to all that social behaviour around smoking. I liked going out on the balcony in the morning in my bathrobe just to smoke. Or go out to the garden with another smoker after a party and have a conversation that wouldn't otherwise happen. Hell, I even liked the gesture of shaking the ashes off a cigarette.
Smoking was also a way to deal with boredom for me, a bit like a smartphone now. I'm waiting for a bus that won't arrive for 15 minutes? That's a great time to smoke a cigarette or two.
To the point: would nicotine patch help me to quit smoking? Probably yes, on the long run. Would gum / snuff / snus limit my craving to cigarettes to the point where I could work in a completely smoke-free place? I do not think so.
I find they do not work. I suspect it's because there are two components to continued smoking. The first is the nicotine addiction. The second is the sensory experience. The act of smoking becomes such an ingrained habit it's hard to stop even when you don't feel cravings. And smoking is pleasurable and relaxing in a way patches and gum aren't. Plus, the gums taste foul and make your throat feel weird.
For smokers, going 4, 6 or 9 hours without smoking is just unthinkable; I know it was for me. So glad I quit (a very long time ago), but I don't know how smokers deal with it today.