Robert M. Gary wrote:

Steven P. McNicoll wrote:

Distance from antenna has nothing to do with MIAs. MIAs and MVAs are
established without regard to distance from antenna.


Are you going to leave us in suspense? What is the MIA based on?

I'm not a controller so I don't know what you call it but I know that
when Lemoore approach is open I can fly over Harris Ranch IFR at 2,000
feet but when they close and Oakland center takes over the min is 8000
feet (quite a difference).

-Robert

Most controllers do not design MIAs or MVAs. It is a specialty, which
requires airspace training beyond what is required to control traffic.

Steve is commenting in the abstract, rather than from real-world practices.

In alt.binaries.pictures.aviation I have posted a two page PDF that
shows both the MIAs (LA Center) and MVAs (Palm Springs TRACON) for an
identical portion of the airspace around Palm Springs.

The title of the posting is:

Palm Springs MIAs MVAs for IFR Group

The file is:

PSP MIAs and MVAs.pdf

Note in particular how much higher the MIA is for the valley floor.
This is because the specialist at Los Angeles Center know they have no
radar coverage down in that valley, thus the MIA design in this case
takes into substantial consideration the center's radar coverage in that
area.

It's a facility call to design MIAs in accordance with what they
consider to be the best fit for their airspace and terrain.