Direct intercept course; VNAV glide path; FMC
Hi,
Just a question concerning the B737NG "direct intercept" feature. I tried to find my answer in books, ask advises to peoples, but nobody have a clear answer for me, so I ask you through this forum guys.
Let's say you are approaching your final airport, and the IAF is called XXX.
You are in a LNAV roll mode, direct to XXX, so you have a magenta line from your present position, to the XXX point, your current track is 090, and you are on VNAV PATH (so on the proper glide path calculated by the FMC to XXX).
Now, you are on a radar vectoring; you press the LEGS page on the FMC, select the XXX point, and set the final approach course to 030, press EXEC, and then you have a magenta runway extension line, and suddently your VNAV glide path on the ND, says you are too high by hundred of foot.
My question, is, how is this "direct intercept" glide path calculated (from which point it calculates that you are too high now from before), is that reliable?
Many thanks,