A filthy dirty habit that infringes on the rights of others that has no place in a modern workplace environment. If you had seen the outflow valves that were removed from DC-9 type aircraft when smoking was common place you would be shocked. Companies should enforce no smoking in airplanes rigidly or face litigation down the track as the community becomes more litigious.
I have worked for companies where crew were given the option, respect the non smoking rule or resign. All except the odd despot stopped smoking in aircraft.