Aluminium-P
From another post:
I think it is worth repeating some information from an American study.
It takes 13 seconds from seeing an aircraft and realising it is going to hit you before your aircraft reacts to your command to avoid the collision.
At typical fast GA speeds at 3 miles head on you have less than 20 seconds to spot the aircraft, and at slower speeds maybe up to 40 seconds.
A good 180 scan takes between 20 and 30 seconds - try it out on your watch.
Next time you are receiving a RIS listen out for the range of the aircraft - see what you can spot when you are told where to look. I do the same with RIS and TCAS - it is really interesting the distances on most days at which you see the traffic WHEN you know where to look.
In short, dont kid yourself, see and avoid really doesnt work at all well - I think it may be one of the significant myths of light avaition.
The real reason there are so few collisions is due to the big sky or electronically aided avoidance.