One thing that I think is clear is that it cannot be economical to open and run (heat, maintain, staff etc) the existing terminal for sometimes as little as one flight a day. Commercially orientated management (without the State as a back up) should by now have taken the fight back to Ryanair and made it clear that the airport was not run for FR's convenience and that they were not prepared to open the terminal for one flight a day and that Ryanair had to run a "reasonable" program or nothing at all.If the answer was "nothing at all" then at least the management could look at what costs could be saved by mothballing the terminal and concentrating on other activities. I have no desire to see the demise of Prestwick but continuing to keep that terminal, designed for transatlantic flights in the 60s, open for a handful of FR flights doesn't make sense. Only if I see some action being taken to seriously reduce costs in that area will I start to believe that the management team has got some commercial nous.
The trouble with the "nothing at all" approach is it also means nothing at all in the summer, when passenger throughput may cover the costs of keeping the terminal open. You need to look at the bigger picture, and not just worry about the current 1 flight a day and associated costs.
They need to keep the terminal open, and passengers flowing regardless of the numbers, so that they may stand a hope of attracting other operators in future. What if EuroLoCo starts to look at the airport, and sees that the terminal is closed during the winter? It's going to put them off launching that once daily flight they were considering.