Often, the elevation of an ILS component is not listed in our nav database.

Often, the elevation of an ILS component is not listed in our nav database.
A good elevation is critical for proper glide slope modeling.  This patch
assigns the average field elevation to any ILS component that doesn't have
a valid elevation.

Also, for an ILS approach, use the GS transmitter elevation for glide slope
calculations rather than the localizer elevation, in some cases this can
make a big difference.