On Tue, 04 Oct 2005 10:46:41 -0500, Chris W wrote:

If you were about to go on an IFR flight, and for some unknown,
hypothetical reason you had to pick one instrument in the standard six
pack that you could not use, which one would it be?

DG (i have a compass, and a GPS with HSI yoke mounted).

Airspeed would be my next option. Again, GPS/DME Groundspeed, plus
pitch/power.