How to Escape a Heel Hook
Heel Hook Escapes
The heel hook is the mother of all submissions in the way virtually everyone feels helpless and panicked when the submission sets in. As a result, escapes are in high demand, and well worth researching. As a caveat, you should always tap well before any sort of pain comes on with a heel hook. Caution should be the guiding principle, as no "lab time" on the mat is worth acquiring a torn ACL. Nevertheless, the following escapes are the highest percentage, safest escapes I've ever seen or practiced, and I've practiced a lot of escapes over the years.
Basic Turning Away Escape
This escape, sometimes called the "runaway!" escape (in homage to Monty Python and the Holy Grail, of course) is your first choice in heel hook escapes. This escape absolutely needs to be preemptive, and all heel hook escapes need to fit into that category. As your partner snakes your leg with a heel hook set up from the bottom, start by turning away, going with the way they're reaping your knee, forcing it to turn inward. Spin all the way around, 180 degrees, before throwing a "marching band knee" (or Muay Thai knee) while pointing your toes. If your toes aren't pointed, your foot will get stuck on their leg as you try to retract. Spin back in to reengage your partner.
This heel hook escape drill relies on a basic knowledge of the heel hook escape described previously, but done with tons of repetitions in a short period of time. The attacker (bottom person) shouldn't try cranking on the heel hook itself, as your response should be in place much earlier than this, but their leg positioning should be correct and enthusiastic. Gradually work up the pace until you're both moving at a fairly realistic competition pace, and get in as many repetitions as you can in a short period of time. The key is to see it coming a mile away and to start turning away right as they start trying to reap your knee.
Watch the Calf Slicer
As a bonus, here's a way to set up another submission as your opponent (mostly correctly) performs the runaway escape. As your partner's leg turns away from you, turn your reaping leg perpendicular with your partner's knee and calf, ultimately settling your shin in at a T behind your partner's knee. Turn your foot outward so you can hook the back of their knee with your foot as well. Make sure their foot is trapped by your hip, and then sit up so that you can hug around their hip. This submission is absolutely capable of ripping your knee apart, so use extreme caution, especially at first, and make sure your instructor knows what you're up to. Obviously, this second submission needs to be taken into account, so the "marching band knee" portion of the move is of the utmost importance!
Heel Hook or Calf Slicer?
Keeping in mind that it took me around 20 years to feel as comfortable as I do now with defending and attacking heel hooks, it definitely doesn't have to take you as long. There is so much more information available these days, and most gyms are starting to practice leglocks with some kind of recurring regularity. While the knowledge base has grown tremendously, you still need to be extremely careful with any sort of leg attack submission, and that goes doubly for heel hooks, simply because there's still a great deal of ignorance out there. Hopefully this helps bridge the gap in your own knowledge base. As always, please let me know how these techniques are working for you!