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wrote:
Yeah, the QEII (I think) ran aground about 20 years ago just off the
Elizabeth Islands on Cape Cod and in one of the most heavily traveled
areas of New England. The chart turned out to be wrong.

Is that the case? I heard about something similar but not a case of a
chart being wrong. A cruise liner enroute to Boston was under autopilot
but the gps lost lock for an extended period of time. During that period
the course was continued with the unit doing its own dead reckoning. By
the time it regained lock it was well off course and the new course to
the next waypoint took it over some rocks. None of the crew had noticed
the system had lost lock and all were trusting that the "gps referenced
autopilot" was safely steering the ship waypoint to waypoint. They also
did not bother to look and see that their course was now taking them
over the rocks.

I believe in the case of the QE2, the rock was charted but the depth was
wrong, plus they didn't allow for squat.
In the other case the antenna was disconnected to the GPS which forced
the system to go on DR, which coupled with other procedure errors ended
them on a sandbar.
Overall, the accuracy of existing charts is amazing considering the
equipment available for the original calculations, etc..
However, many need updating and upgrading for accuracy and and content
and this is going to be a slow process.

otn