One team being smart enough to not destroy a bailed tank is rare but it does happen occasionally. Usually the tank is destroyed, either by friendly tankers who don't know it's bailed or by noobs for the sheer pleasure of blowing things up. But it does happen. Yesterday on Hurtgen an M10 driver rushed in Germeter and got wanged by a sniper, and common sense as it rarely does prevailed, and the Germans left the M10 to sit there until the end of the round, denying the Americans the opportunity of having a fresh one delivered to Katzenhardt.
The best example I've seen of this was on Lebisey, months ago, when a Tiger got bailed in between the two Southern flags and was defended by the Brits as though it was there own for several minutes. All attempts by German infantry to sneak back into the Tiger or kubelkaze up to it were unsuccessful (it was by that garage sort of house, way out in the open). The Germans were finally left with no alternative but to throw Panzerschreks at it until it blew up, just so it would respawn.
This only took one Panzerschrek, as this happened in 2.4..
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I don't mind people bailing tanks. A lot of the time they genuinely do bail to repair, but your kill shot on the tank blew it up and sent the grease monkey sailing off into oblivion as well. You'll get the odd person here and there who really does just bail and run away, but those players are yelled at so thoroughly they usually stop doing it. Indeed, sometimes the amount of shit thrown at a guy for bailing a tank harkens back to the old FH1 days when you could jump into enemy vehicles, a la an American King Tiger rampage on Battle of the Bulge. I fondly remember being on the British team in Arnhem one round when a Jagdpanther was bailed and went on, in British hands, to completely shut down the bridge for the rest of the round. I don't bail tanks except when there is a genuinely good reason to, like if my Panzer II is one second away from barbecuing me on Fall of Tobruk and I am literally five feet away from the cap radius of a flag we're trying to get. I don't really have a problem with players doing that, it encourages me to be more creative and try for 1-shot kills. I can understand how some people might think it's unfair when tanks get bailed, but I think there's something to be said for the fact that if you give them an opportunity to bail, in a sense, you've made a mistake.
Planes on the other hand I shamelessly bail, but I always take a pilot kit. Serious pilots/assholes will take wrenches like Horst said, and he is quite right. But for me personally, I'm not a serious pilot (although undoubtedly an asshole), the only times I ever take planes are either when one's been sitting unused for a few minutes, or else taking the scout plane. On both occasions I will take a pilot kit, because you really can make something happen with nothing but a pistol and a smoke grenade. On Mareth Line we (Allies) once captured Matmata, when there was only 1 guy there and I bailed after being torn up by the 109. The 1 guy already at the flag couldn't cap it himself, but I parachuted down and helped out and we got it captured. Even better was as Germans on El Alamein, when I captured the northernmost flag after a parachute adventure, allowing half the German team to spawn there and providing the turning point in the battle*.
*Okay, we still got our asses kicked. But we held that flag for a good ten minutes against all attacks, and that never would have happened if I had stayed in my plane on some ridiculous notion that a guy who hasn't killed me deserved to kill me.
I don't really think anyone deserves anything. When the opportunity is there to shoot the pilot right out of the plane, why should I let you blow up my plane because you failed to do that? When the opportunity was there, with a bit more cunning on your part, to 1-shot kill my tank, why should I die and lose everything I have because you chose to start lobbing shells at me from half the map away? The enemy doesn't "deserve" a kill any more than I deserve to be killed. Logically, if simply firing a shell that doesn't kill me means he deserves to kill me, then it follows that if I bail and shoot at nearby enemy infantry, I deserv to kill them, even if I missed. I personally don't care about rankings or any of that beyond the rare treat of getting a silver Rifleman medal or something like that. But if it's all about stats, and people are mad that their stats don't reflect a kill they feel they should have had, why is it not a reasonable response to that for the enemy tanker to say "I care about my stats too and I'm not adding one more death to my total every time someone sets my tank on fire"?
Bailing without a chute, however, is definitely a bitch move. Anyone who does that deserves all the shit they get for it.