("Doug" wrote)
You HAVE to have a backup to GPS and USE it. Some sort of non-GPS
system.


Like the signal from an AM radio station?

One of the more interesting links/stories posted in a while.
http://www.tsb.gc.ca/en/publications/reflexions/air/2005/issue_28/air_issue28_sec2.asp#over

(From the report)
The controller was unable to see or identify the aircraft on radar, and
requested that C-GKFJ tune in the low-frequency radio broadcast station 2YA,
frequency 567 kHz, and report the bearing. The crew reported that automatic
direction finding homing was very poor because of thunderstorm activity, but
the most reliable bearing appeared to be astern.


Pilot: We're 80 miles out.
Control: Um, we don't see you on our radar.
Pilot: Yup, we're right here.
Control: No you're not. Tune in to our local Top 40 radio station for a
fix.
Pilot: Hmm. Must be having radio problems, can't seem to pick it up.

Me: That's because you're flying off course to friggn' Antarctica and
don't know it!!!

Glad it all worked out. Whew.


Montblack