I never use a tank to camp and spawn kill, because it's obnoxious. I do love taking off sideways or escaping a spawnkiller by using retry-timing, and then swooping back over and riddling him with bullets. Big challenge to do it, very fulfilling to pull it off.
I often stick around after dropping a bomb on the enemy carrier or base (in Bomb Carrier or Bomb Airport) to shoot enemy planes, to "make a hole" for my teammates with bombs. This is not only strategic, it's often the only way for pilots of new or mid-level skill to get through. I am mid-level, and I appreciate this when someone does it for me. I don't often kill planes on the runway, because the timing is hard (for those who strategically time their reentry, HINT!), but once in a while, a non-immune tank is sitting pretty, so I shoot. Speaking of immune, another reason not to do runway kills is because they might be immune and you are putting yourself at risk if being shot when lining up for anyone, and immunes are a waste of time and risk.
Oh and if I am a tank and have made it to the enemy airport (in Bomb Airport), I may shoot a spawn to keep the air clear of enemies, bur my main focus is hangars baby!
I have certainly been a soldier on a carrier in Capture Carrier. This moves the meter, and you can kill enemy planes that land, and I'd you are good, shoot enemies in the air or on approach. These area all goals of the game. But I am rethinking this, since carrier soldiers are buggy in their visibility (I see flashes of names, then they disappear), and therefore have unfair advantage until the bug is fixed. Well, they are limited in bullets, so it's not overwhelmingly unfair, just somewhat unfair.
Manfred