No it's not... I've had my copenhagen along on many flights. It's a lifesaver.
It may not be banned by the TSA, but as of my most recent commercial flight about a month ago, the flight attendants announced that smokeless tobacco use was not permitted on the flight. It may be a specific airline rule (United) but in this day and age, noncompliance with the instructions of the flight crew can get still make things at your arrival pretty uncomfortable.