Comment by wat10000

There is "the" no-fly list maintained by the government, which is nominally for people who are too dangerous to be allowed on an airplane, yet not dangerous enough to charge criminally.

But each airline also maintains their own internal no-fly list for people they prefer to no longer have as customers, for whatever reason. You might end up on this for some abuse of the system that doesn't pose any sort of safety risk, so the government doesn't care, but the airline doesn't like. For example, excessively doing hidden-city ticketing (where you book a flight with a connection, then skip the second leg of the trip, because weird pricing rules make it cheaper than just booking a ticket to the connecting city) can get you banned from the airline, but the government would be completely uninterested.