Permanent-Part-Time is very popular with charter operators, as it allows them to keep pilots on a permanent contract, but also allows them to release them over the winter season. Best of both worlds really.
Of course, this allows the pilots to seek contract work over the winter if they want to. So it also allows them a little freedom.
It is expensive for the operator though, as has been mentioned above, regarding sim, medical renewals, etc, as you have twice the amount of pilots
