Interesting consequence of improperly programming GPS route

"Jose" wrote in message news:0eCse.1053

What would you suggest as a backup in the middle of the
Pacific Ocean?

Paper charts, a compass, and dead reckoning.

In a manner of speaking, you're sort of right. I've never flew oceanic with
GPS, only inertial, and we always had to maintain a plot. The best backup
is a disciplined procedure, common sense, a plotting chart, and paying
attention.

Bob probably used similar procedures. During pre-flight setup the PNF (I
think) would read the waypoints from the flight plan, and the PF would enter
them in the keypad. For crosscheck, the PNF would read the waypoints from
the display, with the FE monitoring, and the PF would verify back to the
same printed flightplan.

The inflight loading of downline waypoints was a weaker link, but similar
crosscheck procedures applied.

We would have to verify each waypoint passage, plus do a position check 10
minutes past each waypoint, crosschecking each of the three inertial units.
The weak link with inertials, of course, is that the one driving the
airplane will *always* tell you its right on the money.

The leg that crossed the equator or the 180 meridian was always one of the
downline points, loaded enroute, and a wrong entry would result in a wrong
way turn. The guys in this incident were unfortunate in that their route of
flight was close enough to true south that a reversal error did not result
in too outrageous a turn. When I was flying the So Pacific, it was usually
from Pago or Nadi southwestward toward Sydney or Melbourne, so a missed
longitude entry at the 180 would result in such an obvious wrong turn it
would be immediately noticable.