I think taking away some brightness would be the opposite of what you should do, because it looks as if the "bad exposure" refers to the picture being dark overall, due to the overcast conditions as lack of direct light, especially when you include the gray fuselage of the UAL Airbus. If anything, you need to increase the brightness if you can, without washing out the image. You can try to adjust the levels for the whole picture, or just isolate the aircraft and adjust the levels. That may help.
I like the shot; it's a nice "atmosphere" shot. But I think the general preference is for shots in almost ideal light conditions, so even if you do brighten it up a bit, they may kick it back for aesthetic reasons.
(fellow Polish aviation photographer