Originally Posted by
mabg88
I'm curious about the calculations because for the past 9 years I've operated in and out of VNKT shooting the VOR which works well. Now the airport has installed a LOC antenna and they have a LOC only approach. Charted Altitudes and distance to cross check with mcdu are totally off meaning waypoints based on distance are not matching the chart same goes with the altitudes. Was curious to see if the chart was the issue by trying to understand the calculations. Sorry I'm not allowed to post URLs, was gonna show the LOC only app into KTM.
Thank you all for the replies, much appreciated.
You mean VNKT, in Nepal, with lots of mountains? The LOC approach has a 5.4º gradient from the FAF to 5.5 DME and then a 3.0º gradient from 5.5 DME to the threshold.
The 3.0º gradient is approximately 320' x distance to the threshold plus 4320 runway elevation plus 50' TCH. That formula gets me 5586' at 5.5 DME vs the charted 5590'.