Newbie here. I was an umpire at a JV game Saturday. We had movement on the offensive line which was flagged but not blown dead by either linesman or the referee. I didn't see movement. The play goes on and A gains a first down. The WH consults with the HL and LJ who both threw the flag, explained the play should have been blown dead before the snap, waved off the flag and let the play stand, saying it was a dead ball foul and should have been blown dead. Since it wasn't, play stands. Was this the correct ruling?
We got roundly booed and the coach went ballistic.

The correct ruling is you tuck your tail between your legs and enforce a DEAD Ball foul for the false start.

To let it stand is just wrong.

You can easily handle this by rephrasing your penalty announcement. I had this happen in a freshman game about 6 years ago and it worked just fine. We talked about it with the official of course and it never happened again.

Instead of saying "dead ball foul, false start offense, 5-yard penalty, it remains 1st down" we changed it to something like...

"prior to the snap, false start offense....." (something like the NFL does)

The coaches knew we had a flag and were expecting something to be announced any way and were OK with the mistake because we got it right.

Now if you also had a foul on defense during the play then you might need to think about rule 1.6 and handle it the best way you see fit depending on the situation.

When working with associates at sub varsity games on this I will change the dead ball false start to a live ball illegal shift and let the defense have their choice. I will then spend the majority of the ride home having them repeat dead ball fouls to me :)

Fortunately I don't R varsity yet, but if I did and both my HL and LJ saw a false start and didn't blow their whistles, they would be buying pizza and beer for the meetings for a month but I would do it properly and tell the coach we made a mistake letting the play go and give the defense the dead ball penalty option.

Agreed. It doesn't happen here much in JV/MS/HS games, but when I referee flag on campus it happens a lot. Live ball encroachments, live ball false starts, etc. I'll talk to the official that threw it, tell him that that is a dead ball penalty, and then cover him.

I'll change the penalty to illegal formation, tell the offensive captain that he lined up incorrectly, and give the option to the defense. It's worked so far.

Then, on the very next play they'll throw a dead ball illegal motion. I love new officials. :)