Atm, we can be shot down in a b25 attacking ground vehicles by a T34's main gun(or any tank), due to the wrong speed/ground scale (ingame ,compared to ground, planes speed is wrongly represented, and is way too slow compared to real scale), which means planes fly "so slow" (ingame speed scale) that Tanks got time to aim planes flying around with their turret...and shoot them down 
It's so ridiculous, so out-of-realism and ennoying, plz inflight planes must be set immune to Tanks main gun shells to fix that exploit.
In wwii, no tank ever shot a flying plane around with its main gun... 
Hope AH3 will have this fixed.
It is not an exploit or a bug or anything else wrong with the game nor is it "out-of-realism". The problem is that you flew straight at a tank at an angle that allowed the main gun to track and fire on you.
There are recorded instances of tanks during WW2 firing on and shooting down planes. In Otto Carius' book,
Tigers in the Mud, he writes about how he guided his gunner in shooting down an IL2 with their Tiger's main gun during a battle. In Hans Rudel's book,
Stuka Ace, he briefly mentions how his wingman was most likely shot down by a T-34s main gun when he got too low and flew into the gun's range of fire. Dmitriy Loza, in an interview (its also mentioned in his book,
Commanding the Red Army's Sherman tanks; the World War II memoirs of hero of the Soviet Union), talks about using their main gun on their long-barreled (76mm) Shermans to fire at attacking German planes.
The Sherman had an antiaircraft machine gun Browning M2 .50 caliber. Did you use it often?
I don't know why, but one shipment of tanks arrived with machine guns, and another without them. We used this machine gun against both aircraft and ground targets. We used it less frequently against air targets because the Germans were not fools. They bombed either from altitude or from a steep dive. The machine gun was good to 400-600 meters in the vertical. The Germans would drop their bombs from say, 800 meters or higher. He dropped his bomb and departed quickly. Try to shoot the bastard down! So yes, we used it, but it was not very effective. We even used our main gun against aircraft. We placed the tank on the upslope of a hill and fired. But our general impression of the machine gun was good. These machine guns were of great use to us in the war with Japan, against kamikazes. We fired them so much that they got red hot and began to cook off. To this day I have a piece of shrapnel in my head from an antiaircraft machine gun
ack-ack
