How long is a tank protected in spawn?
For me, I notice that my icon stops blinking (no longer protected) at around 3-5 seconds. Yesterday, I had a game where I had sighted a Vidar in his spawn firing his gun. I pulled to the crest of the hill so that I could get my gun on him, (about 5 seconds), fired and had my shot go right through him (2 seconds) He fired again at a target. I then launched an ATGM and had the same result (4 seconds). My main gun reloaded 2 seconds later and I fired again…right through him (4 seconds). During this last part, he turned his tank and gun, fired and killed me about 1 sec after my last shot went through.
Thats a total of ~15 seconds of spawn protection. Not to mention, I saw him fire 2x…third shot was at me.