Umpire Calls PI when...

[BoomerSooner]

Has anyone ever discussed or considered using a discreet signal by which the U can suggest to another official he saw something that might have been missed, or alternatively a signal that the rest of the crew can use to ask the U for help on a PI situation. Could be something simple like the U grabbing the belt buckle to say I think I saw something. Or likewise the B could do the same thing and a quick nod from the U could confirm. I realize there is a lot going on in a short period and we don't want a flag to come out super late in a PI situation, but if practiced could something like this be done? Never heard of this but it came to me as I was reading the other posts because I've also been instructed that the U should just about never flag PI. The "just about" part was followed some cliche "I never say never" or "there is always an exception" type statement, but the point was clear...don't call it.

Generally speaking I think the only plays where the U would even be in the best position to see PI are on plays where a TE tries to clear out a LB where a back runs a route right behind him in the vacated space or on plays where a back appears to move up into the line to block and then slips out for the little 3-4 yard curl for a dump off pass. Those plays pretty much occur right in front of the U, but even then the B, L, or H should be able to get them.