Peril Sensitive Airbag

OK, you're a cheapskate who participates in all manner of hazardous activities (mountainbiking, snow boarding, driving a car made before airbags...) and you want some protection. How about a one-size fits all activities forehead mounted airbag? With advances in modern electronics utilising weird quantum dot kinda stuff, it can't be long before electronics can dimly perceive the future. Thus, a sensor which can sense when something nasty is going to happen is also affixed to your head. So, when you're busy taking your favourite physical risk, you can be sure that in the event of something nasty about to happen, the airbag goes off, preventing a sad contact between face & scenery....Many thanks to the memory of Douglas Adams & his peril sensitive sunglasses....