Originally Posted by IO540 With an altitude encoder you have no way of knowing if it is out of calibration, and if the aircraft in question does not have a transponder then the pilot may never realise it is out
“Does it make sense to have an altitude encoder without a transponder? I often get asked to state my indicated altitude after being given a squawk code, presumably so ATC can confirm if my transponder is working correctly.”
It makes no sense to have an encoder without a transponder as the transponder has to transmit the encoder output. When IO said there was no way of knowing if the calibration was correct, he had probably forgotten that you can ask for a mode c check from just about any radar unit every time you fly if you want to. On modern units you can also display the encoder output on the front panel and compare it with your altimeter set on 1013.
Rod1