ILS approaches and stepdowns

[A Squared]

Just wondering how you calculated that you would reach Larre at 6146?

I started with the TD Zone Elevation, 2069. I added the Threshold Crossing height of 65 feet. This gives you your altitude in MSL at the threshold, on the glideslope. I know this is not exact, as the TDZE is not the same as the threshhold elevation, but it's gonna be close. So the glideslope crosses the threshold at 2134 ft MSL. The GS is three degrees so the tangent of 3 degrees times 6076 ft/NM tells you that the GS slopes 318.4 Ft/NM. LARRE is 12.6 NM from the threshold, so the GS Slopes 4012 ft between LARRE and the threshold. That gives you 6146 MSL