I think with Aces High there is a big gulf between new players and experienced ones which I was thinking might be partially bridged by making the TA a more attractive place to hang round in for both. The TA should ideally be the first point of contact for new players and facilitate learning which it does to an extent, but then there's no real reason for experienced sticks to go there for themselves. I have a few suggestions I thought I'd just lob out there to start some discussion:
Aerial firing range - have drones of various aircraft types flying round in a set pattern like a long-sided oval. This would be better than the gentle circle offline drones fly in. This way you can pop in anytime you feel like and practice your gunnery from every aspect or just to warm up. You can also get help or share advice with those similarly practicing - you can't do that offline.
A permanent target area - I don't think many new players know about the dot commands. Why not hang some targets out there permanently with their own icons to show distance.
A Parcour zone - my Brother had a game on his Nintendo once called Pilot Wings. One of the activities was flying through coloured virtual loops or blobs in the sky which formed a sort of aerial course. If arranged nicely then BFM could be practiced without lengthy reading or studying or even being aware you are doing that. An increasingly difficult course might attract experienced sticks even if they just wanted to check out a new aircraft or challenge themselves for fun. Perhaps a ghost plane of the last person through could encourage innovative routes and manoeuvres.
A Redbull racing area - A lake or an area next to a port which has the pylons as used in the Redbull races. So players can practice racing / flying hard. You could even have a timer system and a scoreboard on a permanent arena page.
Pod Racing course - Some desert terrain with a twisting valley and maybe even the odd cave to fly through.
Batfink Town - Incorporate some chains of hangers, ships and obstactles from Batfink's excellent terrain. This is really fun and challenging.
A BFM Bot - Which could be set to demonstrate manoeuvres and left running so players could follow and learn. Would also help with the different consequences of pursuit curves.
A Gliding School. An Alpine-like bit of terrain with an airspawning modern glider or even a period open wooden and canvas one. Germany used gliders to train a shed-load of pilots when they were forbidden to use powered trainers and as stick and rudder is so fundamental to flight this would be a good training tool, even for experienced pilots. The core of energy conservation habbits could be formed or revised here. Could have a feature which modeled a thermal column to increase endurance. Might be a good way to hook new subscribing players if this was only available in the TA.
A question pin board - On a similar tab to the Arena message, where players can leave questions and whoever happens along can answer. Not many new players have a forum account this might be more convenient.
Three month free subscription - yeah baby, three free months but for the first two you are only allowed in the TA - think about it!
A squadron notice board - as players approach being let loose in the main arenas, they might request a trainee position in an established squadron. Similarly squadrons could offer positions for those wanting to learn. Hopefully this would buffer some of the noobshock when you start fighting in the MA. I bet a lot of potential long-term players are lost to that.
Perhaps some of these ideas would help to streamline new players into the game and at the same time offering some variety of flying activities for established players too. That way the one can meet the other on friendly terms instead of getting frustrated at being pwned twelve times in a row then quitting. Has to be better than the old alt f4 tradition. Some of these suggestions wouldn't take so much work. Perhaps some of the terrain ideas could even be implemented by one of the players who build these things.
Well just some creative ideas for what they are worth.