[AtlUmpSteve]

One mechanic the NCAA manual urges is that the base umpire, on seeing a situation and deciding it is a "no call", should give a "safe" signal. If I see that as PU, I am poaching if I now rule; if BU makes eye contact, we can work out quickly if s/he has it or is looking for assistance (most likely, because no signal, either "safe". or "dead ball", or DDB, means s/he saw something, but doesn't have a clear decision because of position). No signal at all, and no eye contact, tells me that BU hasn't even seen the situation to recognize the situation even needs addressing.

Again, delay and read BU, who has primary responsibility; but, make the call if necessary.