(C Kingsbury) wrote:
The conservative choice would be to listen to the first box that cries
"miss." Let's say the wind shifts and your groundspeed changes, the
handheld says you're there. Might be good to miss it. If OTOH the
clock says you're there and the GPS doesn't, you're not going to
increase your risks by missing on that basis.

I don't know if I agree with that. Let's say your calculations are
wrong and the timer runs out when you're 1/2 mile from the MAP. Which
has less overall risk:

1) Continuing another 1/2 mile to the real geographic MAP based on your
GPS, finding the runway, and landing uneventfully.

2) Going missed, and being back in the clouds trying to decide if you
should try the approach again or divert.

#1 sure sounds safer to me.