"otnmbrd" wrote in message
ink.net...
Rodney Myrvaagnes wrote:

Actually, the GPS was not in use. It was just that nobody thought to
check if it was for 600 nm. Reconnecting the antenna would have solved
the problem, as would have several of the other things nobody bothered
to check.

They were "integrated-bridge-system centric." A significant
difference.

It's a point, but let me explain why I'd put the main blame to "GPS
centric".
When they left Bermuda they had three systems available for Navigation.
GPS, Loran, Celestial. Since the GPS wasn't working, the integrated system
reverted to DR (and obviously did a damn fine job, considering) and
followed the prescribed track (here, I'm not sure of a doppler input).
Other than a cursory check of the Loran and, it would appear, no system
check of the GPS (no celestial was used) the "system" was allowed to
proceed.... i.e., the Loran positions were not all that far from the
assumed GPS.

Sure they were. by the time they were 200 miles out they had a multiple
mile error.

The chief officier and navigator both stated that a cross check of the LORAN
was done. The second officier stated the LORAN was used only as a backup to
the GPS.

The NTSB found that the LORAN was never checked and should have been.


Now, on the approach to the Nantucket-Boston Safety Fairway, things should
have changed. Your Loran is pretty good, You come on soundings, You have
Radar Targets, You can make allowances to use visual checks, You know
there are strong, contrary currents in the area, but none of these tools
were seriously used and none of the dangers were considered.
Why? Because the navigators were GPS centric, believing their Nav Plotter
was getting the correct information from the GPS and not using other
"systems" to confirm that this information was correct.
The fault here was not GPS nor the integrated system. The fault here was
navigators relying solely on one system to be correct all the time.

They had failure indicators staring them in the face the whole time. They
just never looked. Makes little difference what the failure is if the
indicator is not noted.


If you are going to be navigating, you want back-ups to your back-ups.
Sure, You can carry 20 hand helds and 4 cases of batteries, but what
happens when the Chit, negatively hits the fan and all you know is GPS?

No they were simply not very competent. They were plotting the positions
hourly...but taking the positon from the busted system. Plotting the
positon from one of your 20 handhelds would have blown the whistle before
they were an hour into the failure.

What happens when the system fails and you are not aware of it and you go
merrily on your way, believing it's working?
No, they were GPS Centric. They believed everything was fine, when a
system check would have said otherwise. They didn't use back-ups/double
checks, they believed the GPS would always work so consequently the
integrated nav system must be correct and never needed checking on, for
whatever reason.

Basically what I'm saying is go back to the first basic error. The GPS
wasn't working, no one checked to see if it was... they were "centric" in
that they assumed it would be, when in truth, for any number of reasons it
may not be and the prudent navigator realizes this and checks, especially
in areas such as the Nantucket-Boston Safety Fairway.

otn

And a major finding was that the system design was deficient in a number of
human factor ways that provided the environment for the grounding. For
instance the GPS had a suitable external alarm...which was not hooked up.
The report strongly suggest that redundant receivers should also have been
part of the system. The system should have cross checked the LORAN and the
GPS. All kind of simple stuff.

Jim