FD
"If altimeter readings would be transmitted, you would see me jump up and down as I change the altimeter"
We do see your altitudes jump up and down on the radar when wrong QNH is set on your altimeter and the QNH is subsequently changed, thats why we challenge the levels for separation.
Example...
An example in this FIR with our adjacent FIR Tehran. An inbound acft was at FL120, our transition layer is FL140. At the same exit/entry point an outbound is on QNH flying at A110, inbound the aircraft at FL120 on 1013. Our QNH was 997, the difference of 16Hpa which had the inbound aircraft at A116 which A. on radar would be a loss of separation, B.I f the aircraft were on conflicting courses/climbs descents etc. it should give a TCAS alert????