Hey, I was thinking about ways allied pilots could signal without using microphones, and the idea popped into my head.
The flare gun would just be a small, handheld pistol that launches a harmless flare in the direction you shoot. Unlike the flare gun turret, this flare gun would not set anything on fire and would not illuminate clouds. Left clicking the gun could fire a flare, and right clicking could deploy it (or it could forcibly deploy at a set distance, or on contact). Once deployed, the flare would show up through obstructions with a coloured bracket (coloured for your team), similar to the brackets used to highlight enemy ships. The flare itself would also burn with the colour of your team.
This would allow you to pre-organise specific locations that you can tag in-game, or to use with chat/voice chat to assist in relaying tactics in-game. If you want an ally to go and guard a specific area, or lay mines in a particular part of a canyon, or to go and capture a certain point, or flank from a certain direction, you could just fire off a flare to show them exactly where you mean, rather than trying to use a grid reference on some of the big maps.
The function of this idea would work best if flares could only be seen by allies on your team, so the enemy cannot see your flare and act upon it. The flares could show up as a small star, or asterisk on the map, for your team-mates to view. Furthermore, if it is possible, each flare could be numbered by order of launch and possibly given a letter to indicate which ship fired it, to avoid confusion from the use of multiple flares.
This gun would work well for pilots, since pilots rarely have an opportunity to use gun turrets, and therefor usually have no need to bring ammunition in the gunners tool slot. It would also work well for crew in other positions, either a gunner who doesn't need all their ammo slots, or an engineer who isn't using any guns (or doesn't need ammo for the ones they are using).
As an additional feature, the flares could be used to outline mines. For this purpose the projectile would act like the projectile from the flare gun turret, and deploy on contact. preferably, this should not contribute to the numbered flare symbols on the map, but maybe just a small mine icon (spikey ball) instead, or not have any map symbol at all. In normal view, the flare on the mine would shine the colour of your team, and have the bracket outline to show you the location through any obstructions. It also means that if you are laying mines, you can flag them so your team mate(s) don't accidentally hit them.
Ideally, there should be a low maximum amount of flares per player (one or two I was thinking), to prevent confusion and prevent people from using them irresponsibly (as trolls are likely to attempt). The best possible anti-abuse solution i could think of was to make it so only the player in the Commander slot of a ship can use the deploy feature, to limit regular players to tagging mines. That way, there is no way for regular crew to 'spam' the flares as a distraction, since the only thing they will be capable of doing with it is being helpful. Flares would most likely need a set duration, and they would need to 'burn out' when more flares are fired past the limit, the same way the oldest mine is destroyed when a new one is fired past the limit.
I'd love to hear some alternate ideas/modifications you guys have!