SIMPLE.
if you think its safer for the aircraft to go around, tell it.
on the other hand, if the aircraft is in an emergency situation, there could be a flock of ostriches running up and down the runway, and it won't matter.......THE PILOT WILL GET THE PLANE ON THE GROUND...ASAP!
relax, you're not expected to be an expert on air traffic procedure.
just go with your gut, commonsense feeling.
good luck,
the lucky one
