Originally Posted by Ripplewind
Always let the horse see it. Don't play the "Momma" figure and try to make it less scary for them. Unlike children, horses have to be able to care for themselves, otherwise they wouldn't survive. I would ask the horse to keep going, and eventually he or she will learn that the bus is not going to eat him or her.
They NEED to trust their handler and not 'care' for themselves. When a horse is attached to a leadrope or reins, the leadership role belongs to the human at the other end.
I keep riding but have an exit strategy in case they spook or have a rock fly and smack them. Be aware of holes in the ditch, rocks, fence, mail box, culverts, etc.