In article ,
wrote:

You are right, Xponder is not a serious problem in our situation. We
didn't consider it a serious problem or we wouldn't have left KMBO.

It **could have been** a more serious problem had we been inside
Charlie or Bravo airspace.

I've had a mode C failure inside the SFO Bravo surface area. I
was northbound along 101 for the Bay Tour at 3500ft. ATC let me
continue, but had me maintain 2000ft for my tour (normally, as long
as you stay outside the Bravo, they dont't care about your altitude).
After the tour, I was cleared through the Bravo again for the return
to PAO. The only issue was PAO tower was a bit miffed that my mode
C was out, but NorCal didn't have a problem with it across several
controllers.

John
--
John Clear - http://www.clear-prop.org/