Doug wrote:
One difference I have not seen mentioned is how the VFR GPS appears in
the scan and relates to the other instruments. I know having a
permanently mounted, cable free installation where everything is always
where it's supposed to be makes a difference in the usability of an
instrument. This is one reason why I don't think we will ever see IFR
certified handhelds. The installation is part of the certification.


The TSO for IFR certification of the avionics and the installation
requires RAIM, auto CDI scaling, panel mount, display on the CDI or HSI
in the primary field of view (your point), demonstration that other
installed avionics will not interfere with the performance of the GPS
avionics, and a switch to select conventional nav or GPS to the primary
display.

A hand-held does none of the above. ;-)