Andrew Sarangan wrote:
Peter R. wrote:

Andrew Sarangan wrote:


Something I never understood is why LNAV approaches don't automatically
show a glideslope so that the airplane arrives at the MDA at the VDP.

Perhaps because it wasn't part of the certification at the time?



Perhaps my comment was not clearly stated. When you fly an LNAV
approach (or any nonprecision approach for that matter) instead of the
traditional dive and drive you can mentally calculate the vertical
speed required (VSR) to arrive at the VDP at a constant glide angle .
That mental calculation could be easily performed by the GPS and
displayed as a glideslope. But I have not seen any GPS do that.
Certification is irrelevant. We are not talking about a lower minimum
or anything new that we not already allowed to do.



Perhaps because that functionality is not at all desirable. The "dive
and drive" term is derisive, however, it is important to get to minimums
in order to be able to see the airport. Arriving right at the minimum
altitude just as you reach the place/time for going missed does not do
you any favors.