Use DA or MDA in RNAV with Displaced Threshold?
Hello gals and gents,
This doubt has come up occasionally where we operate.
There is a 3000m runway that got one of the thresholds displaced 350m, so now it has only 2650m available. The current IFR procedure available to this runway is a RNAV with a 3 degree angle. Our equipment has VNAV PATH guidance and GP (Glide Path) capabilites to intercept and follow the CDA of 3º.
However, the doubt rose from the fact the glidepath leads you to the aiming point, 1000' mark. Since the threshold is displaced, now the glidepath leads us to the beginning of the displaced threshold.
Some argue we shouldn't use the DA minimums, and instead the MDA minimums (something like 80' more).
Others argue that we should not even use the Approach capability to intercept the glidepath, and instead do a dive-and-drive, considering it a non-precision approach (arguing that this is like a LOC only approach with an U/S GS) and reach MDA, level out until we reach the VDP.
I haven't really searched much, but in our regulations, manuals and SOP there isn't such situation described.
I have yet to search ICAO documents.
Any input from you would be greatly appreciated!
Thanks!