Transponder: Difference between revisions

See [[this page]] for official description. Civilian Mode-S and Mode-C both transmit pressure altitude (at 10-foot and 100-foot precision, respectively). To do this the transponder needs an altitude source. In real-life this can be a separate box called an encoder, or may be derived for FMC / ADIRU sources. It's important to note this altitude is referenced to standard pressure (29.92 inHg / 1012Hpa), and not corrected for actual barometric pressure in the local environment.