There appears to be two different discussions happening here! TCAS and Mode S, which are very different beasts…
Crash One
TCAS or ACAS, generally speaking, is a system used by commercial operators and I believe it’s fitted to a number of non-civilian types. It works on the principle on the SSR, where a signal is sent by one a/c, searching for responses from transponders within a selected range, in both the vertical and horizontal. Where found, the system will calculate if a conflict occurs and give either a TA (traffic advisory) where no conflict occurs at that point in time, or RA (resolution advisory) when you are given guidance on how to manoeuvre you’re a/c to avoid collision.
If you are operating in the light a/c GA world, this system is financially prohibitive. Having a quick look at the Honeywell site gives a shock to the system – I didn’t realise they were that expensive!! There are cheap systems on the market, but is your life really worth so little!! See and avoid……
Assuming you operate in this environment and as your profile suggests, Scotland where we have a huge chunk of Class G, having a Mode C transponder installed at say £1500 - £2k is almost a no brainer. It will assist flight safety to a great deal and also assist ATC in accurately identifying your position – no bad thing if you ask me.
Mode S, in my opinion is a very different matter…
As I understand, the main push behind this system is for accountability and financial reasons from the Campaign Against Aviation, where your flight details are recorded and bills issued for use of the airspace. I can’t see how it provides any further help in flight safety over the current Mode C equipment.
The table posted by Beagle seems to be a very simple and sensible proposal, but then that’s not going to make very much money for those in the big grey building. I agree that mandatory usage is not unreasonable, but it must not be a sweeping all must carry Mode S statement.
Robin – I can’t see why such agreements would stop. Your types under from the table above would require no more than a simple Mode C unit. To be honest, you may even be asked not to use it within certain parts of Class D to minimise RA’s and the resulting MOR’s.