Hey? Why would a tribunal overturn a correctly reasoned dismissal by an employer? What BASSA and most of their followers fail to realise is that employers do not have to prove guilt beyond reasonable doubt just guilt based on the balance of probabilities. So if you were, by way of example, standing outside the crew car park on a strike day with a telephoto lens and a notepad and had been seen by several arriving crew members and managers taking pictures of crew would it be unreasonable to deduce that you were up to no good?
I'm not suggesting the above actually happened but you are not talking DNA evidence and a jury trial here. A manager must decide given the balance of probability what you were doing and whether that was in keeping with company rules.
My understanding is (thanks to Google!) a tribunal will only consider whether the company followed their own processes in dismissing you, not whether you are/were actually guilty or whether the punishment fits the crime. Is that what you understand ET consider?