Thanks for sharing, and glad nobody died.
Out of curiosity, was the rider wearing an air bag pack?
Also, with regards to checking your beacon:
It is a good idea that someone mentioned about the lead rider checking to make sure everyone's beacon is working. However, I will add that it would be an even better idea if everyone checked theirs in both the receive AND transmit modes. It will take up more time, but at least you will know that EVERYONE'S beacon is functioning the way it should be in the event of an emergency.