Good initiative!
There is indeed no real way to know in advance who is online, AFAIK.
On the website, under the "Latest Flights" button, you can also see the current flights, but that's only when the flight is already underway, I believe. Or at least when FL is recording a flight. (Not sure if it only takes FL data, or also IVAO / VatSim network data). At least the forum gives a chance to communicate a bit back and forth before the flight.
On the other hand, with only 19 active pilots at the moment, the chance of being spontaneously online at the same time is not very high, of course. Maybe we should use this thread to announce our flying intentions (other than maybe the current PP event flight planning which is going on in their respective separate thread). That way, one may postpone their flight for one hour, or a day perhaps, in order to fly together. Which is indeed way more fun to do
