2nd Horn Question

[jeschmit]

I had a sitch last night that I wanted to get some clarification on. Starting the 4th quarter, Team B has all five players out on the court just after the first horn sounds. My partner is already in position under the basket, so he didn't warn Team A about the first horn. Team A is still in the huddle after the second horn sounds, so I blow my whistle, bounce the ball to B and they get an easy layup. At the first stoppage of play where I am next to the coach he tells me that we have to give him a first horn warning so they know to break their huddle. I tell him that our warning is just a courtesy and that they should be ready to play at the second horn.

Was I right, or is our first horn warning not a courtesy?