With respect to setting the DH or MDA does one set it on the radio altimeter or the barometric altimeter??

>With respect to setting the DH or MDA does one set it on the>radio altimeter or the barometric altimeter??The short answer - it depends.The long answer... for non precision approaches you ALWAYS set MDA via the barometric altimeter. For CAT I ILS approaches you generally set MDA via the baro.For CAT II approaches, where the runway environment is specified to be level far enough out for your radar altimeter to be useful, you can set the RADIO minimums to DH.

At every company I have worked for, it has been standard practice to set RAD ALT for any cat II or III approach, MDA for any Non-Precision approach or CAT I precision approach. Many times the reason an ILS is only CAT I is that the TERPS or PAN-OPS charting didn't find enough level terain before the threshold. You may get false minimums calls using the radar altimeter if it is set.I hope that this may help answer any questions you may have,Nate