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.

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.

By using paper charts, a compass, and dead reckoning as backup, I mean
to actually use a plotter, draw a line on the chart, and measure the
course line. Your paper chart indicates (for example) a desired course
of 170, and your GPS says 190. Something's wrong.

It's like working a calculator without doing a rough calculation in your
head at the same time. Press one wrong button and the calculator will
tell you that you have 143,226.21079 gallons left in your 152. I'm
amazed at how many people would just put that down as the answer these
days, because the calculator said so.

Jose
--
"Never trust anything that can think for itself, if you can't see where
it keeps its brain."
(chapter 10 of book 3 - Harry Potter).
for Email, make the obvious change in the address.

"Jose" wrote in message news:IeDse.6352

By using paper charts, a compass, and dead reckoning as backup, I mean to
actually use a plotter, draw a line on the chart, and measure the course
line. Your paper chart indicates (for example) a desired course of 170,
and your GPS says 190. Something's wrong.

Well, I guess I didn't clarify. Oceanic, that's what you do with a plotting
chart. Its a line on paper, but its just a small scale chart so when you
line in the trip pre-flight, you can get the entire trip on one sheet
smaller than an enroute chart. All the DR data that might be needed for
reference...time, distance, course for each leg... is contained on the
computer generated flight plan -- its part of the cross check.
For a local or regional GA flight, your absolutely right -- the GPS data
ought to be periodically back-checked against a chart.

All the DR data that might be needed for
reference...time, distance, course for each leg... is contained on the
computer generated flight plan

.... and if the computer's wrong, do you draw the wrong line on the
chart? We might be saying the same thing here, but I am advocating
drawing the line with =no= computer help whatsoever, and using a plastic
plotter to figure the course lines. This would be totally independent
of the computer, and then when the computer does its thing, you have a
reality check.

Jose
--
"Never trust anything that can think for itself, if you can't see where
it keeps its brain."
(chapter 10 of book 3 - Harry Potter).
for Email, make the obvious change in the address.

On Fri, 17 Jun 2005 22:42:36 GMT, Jose
wrote:

... and if the computer's wrong, do you draw the wrong line on the
chart? We might be saying the same thing here, but I am advocating
drawing the line with =no= computer help whatsoever, and using a plastic
plotter to figure the course lines. This would be totally independent
of the computer, and then when the computer does its thing, you have a
reality check.

Drawing the line on a plotting chart is done with =no= computer help,
which is precisely why the chart is a valid cross check, along with
the "raw data" contained within the Flight Plan.

Jose

-Jack Davis
B737

-J. David
B737

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"Jose" wrote in message news:wlIse.2580

... and if the computer's wrong, do you draw the wrong line on the chart?
We might be saying the same thing here, but I am advocating drawing the
line with =no= computer help whatsoever,

That's actually a little impractical where oceanic crossings are concerned.
Routes are assigned based on several factors, and you only get the
information when the flight plan is generated. The waypoints are merely
Lat/Long points. You could draw the whole thing by hand, but you'd be
starting with computer generated data, anyway.

What you're suggesting is actually covered by quickly pencilling the
assigned route onto the plotting chart, and applying the smell test.

Jose wrote:

PressÂ*oneÂ*wrongÂ*buttonÂ*andÂ*theÂ*calculatorÂ*w ill
tell you that you have 143,226.21079 gallons left in your 152.Â*Â*I'm
amazed at how many people would just put that down as the answer these
days, because the calculator said so.

Nice long-range tanks you've there.

- Andrew

("Andrew Gideon" wrote)
Press one wrong button and the calculator will
tell you that you have 143,226.21079 gallons left in your 152. I'm
amazed at how many people would just put that down as the answer these
days, because the calculator said so.

Nice long-range tanks you've there.


I hope the calculator person noticed that big number and figured "something"
wasn't right.

143,226.21079 is probably pounds, not gallons. Divide by 6 for gallons
(23,871) ...which is almost 1 gallon per mile at the equator :-)

Next: Weight & balance.


Montblack