At AIB you're given a score for each of the modules you're tested on except fitness which is a simple pass/fail. So you'll have a score from planex, leadership test, interview and psychometric tests. If you meet the passmark for your chosen role and you're forwarded for selection you will be put on a list, when the board meets for each BRNC intake they will take the top scoring candidates based on the number of roles open for that intake, so low scoring candidates might end up on that list for some time. I remember hearing that some people are recommended to do AIB again if they have a low passmark to increase the chance that they will be selected.