I built a device like this, which works at 433mhz and is located between the Timer and the ESC and which can turn off the engine in an emergency.
It works on any timer, Fiorotti, Burger, Rubin, KR, Climb an dive, etc.
We recently had 2 accidents with models completely destroyed when a bird attacked a model which caused it to fall and when a model suddenly turned on.
Just yesterday another bird attacked my model and collided with it, luckily the bird and the plane are fine.
I turned off the engine to see if there was any structural damage but all I found were marks from when my cat slept on the wing.