This is yet another 'quick-fix' SI produced by our Ops dept to cover known deficiencies. What is the point in having vertical separation if you can't rely on it? The simple way out of this is either:
1) Log it as a known fault. If you get an SMF or STCA or 'spurious Mode C' readout, confirm the level of the aircraft concerned and there will be no incident. No further action required.
2) Turn the radar off and use procedural separation of 1000ft and we will be none the wiser.
It's just STUPID to be taking this approach, with the only promise of improvement 'in a few years time when Mode S arrives'.
How, in a 10-mile wide airway, do you keep one at FL320 and one at FL300 4 miles laterally separated whilst still having room to climb the Amsterdam departure five miles abeam to FL 360 and always remaining 2 miles inside the airway or within 5 nm of the UAR centreline or the Mil get upset??
Yet another NATS papering over the cracks
