BILL– The first thing to say about teaching flying changes is “don’t make it hard for yourself!” If you decide one day “this is the time” and march out to do battle, you’re setting yourself up to fail.
In the best world, if you can recognize when the horse is in his absolute best balance and alert enough to your aids—almost like he’s saying “if you ask me now, I’ll do it”—that’s the time to try one.
In the greater scheme of things, successful preparation trumps riding any particular pattern haphazardly, no matter how clever the exercise is. Having said that, recognize that a certain amount of anticipation on your horse’s part can work to your advantage, at least for a while. Using one exercise enough times in a row that he’s no longer shocked by your demand and wants to help out gives you more chances to reward him as he learns the mechanism.
You can find a million patterns in the books—asking in the corner or at the end of a short diagonal, after a canter half pass, from one 20-meter circle to another, or on a single circle from counter canter back to the true lead are among them.
One of my favorites is to ride three loop serpentines width of the arena with no change of lead (as you would in the current Second Level Test 1). Then, when your horse is feeling good, as you finish the second (counter) loop and you’re about to head back onto the true lead, change your mind. As you cross the centerline, make the flying change and stay on the center circle.
Whichever way you choose, as soon as he’s changed, reward him. Either land, rebalance, and soothe him as you canter on quietly (either sitting or in two-point) or land and bring him to walk to bask in your praise.