Get Off The Horse!
I can't tell you how many times I've told one of my riders to get off and address something from the ground, or encouraged them to do so when they encounter something dicey. So often this suggestion is met with "but then my horse will learn that if he does something bad he gets relief!" Well, sort of. This assumes two things. 1) The pressure he's upset about is you, and 2) You are aversive simply sitting on his back. Assuming you're a decent rider, neither of those is likely to be true. Typically what happens is the horse is spooking, or his equipment fits poorly, and he's reacting in a manner dangerous for humans (bucking, rearing, etc). When I feel something like that building, I get my own two feet under me and help them through it on the ground. This can actually be even more effective in scary situations for your horse because he can see you and doesn't have to worry about you balancing on his back.
I've honestly yet to meet a horse who had a training problem because his rider CHOSE to step off of his back and work through a situation before it escalated. I see far MORE training problems (and injuries!!) because a rider tried to stay on and "cowboy up" through an unwinnable circumstance. I realize this is somewhat of a controversial viewpoint, so I'd love to hear your thoughts below! To me, human safety is more important in the long run than the horse having a very unlikely chance of learning that thing removes a human he was fine having up there in the first place.