"It's a bit like having the early GPS's that gives you lat and long only. Not very practical."
Adam - you are deluding yourself.
A PCAS that had only a light bulb that came on to warn that an aircraft is within 1 nm would be an improvement over unaided see-and avoid!
Knowing WHEN to look (i.e. STOP whatever else you are doing and lookout in earnest) is valuable.
Sometimes see-and-avoid is all we have and I encourage everyone to develop a thorough and efficient lookout scan - it is difficult to maintain a good lookout and it takes training, practice and discipline.
Be under no illusion though...
- We cannot see through solid objects.
- We can only look in one direction at once.
- We have to attend to in-cockpit tasks and, occassionally at least, look at the instruments!
- The human visual system was designed for sneaking up on antelopes (and it is very good at this) and not for detecting a target on a constant bearing closing at 200 kts (it is rubbish at this)!
For those that think that their lookout is infallible... the aircraft you see most of the time were never going to hit you anyway and you remain oblivious to how many you never see.
I am reasonably confident that my lookout is as good as anyone else's on this forum, if not better, and I have a PCAS (MRX, with lithium ion batteries - works great).
I say again - if you are serious about your flying, and about safety, buy a PCAS!