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    Re: More on That Grounding in the Philippines
    From: Frank Reed
    Date: 2013 Aug 6, 13:36 -0700

    Lu, you wrote:
    "As many have posted before, the skilled navigator uses all sources of information available. The navigator of this ship clearly screwed up by ignoring the crew's reports of sighting the lighthouse."

    The catch is that they may not have properly identified it. These are waters with plenty of traffic. I'm surprised they didn't pick up the "lighthouse" (it's not clear to me that it's active) on radar. Surely they were operating with radar in order to avoid running down local fishing boats (?).

    And you wrote:
    "I'm not sure about the US's NGIA which produces charts of areas outside the US, but the US's National Ocean Survey uses exactly the same database to (automatically) produce paper charts as is used to create electronic ones. Assuming NGIA uses the same technology, "wouldn't have had that problem if they didn't use a chartplotter" is not correct; a paper chart would have shown exactly the same mis-placed reef as the chartplotter did.

    This may not be the case. This article hints at some details which were covered more explicitly in earlier articles. Different scales of digital charts are not produced by "zooming out" from the highest resolution chart. Instead, results are generally superior when various scales are independently produced. It's very difficult to come up with an algorithm that can convert a complex local chart of an island into a simplified structure at a smaller scale. Many algorithms to do this exist, but they all have their weaknesses. Hence independent generation of charts at different scales is still preferred.

    There IS, however, a clear flaw in this mapping process if this reporting is accurate. The article says, "In 2011, NGA obtained survey data that corrected this positioning, but due to a failure to follow established procedure, this correction was made in one portion of the DNC, but not in another, Long said, a mistake she attributed to human error." If there is an opportunity for this type of human error, then something is wrong with their software. It sounds here (and also in earlier reporting) as if someone manually fixed the charting error at one scale, but did not realize that it would have to be fixed separately at other scales, too. But this check should be part of an automated consistency check --not something left to some employee's unfortunately imperfect application of procedure. EVERY TIME a DNC update is released, there should be consistency checks. I am sure that they do exist already, but somehow this basic check has not been implemented.

    You concluded:
    "As most good navigation instructors will say -- if you're not sure about something, STOP and figure it out."

    It's not clear to me that they got to that point. If some junior member of the navigation team, plainly said "that lighthouse is in the wrong place", then that should have set off alarms and, as you say, it's time to "stop and figure it out." But if the crewmember show sighted the lighthouse instead only noted "a light off the port bow" or something like that, then they may never have gotten to the point where they realized that this was a navigation conflict. They may well have thought it was a squid-fishing boat, for example. They often mount very bright lights to attract squid (squid boats are plainly visible from orbit at night).

    There's one other point in this article that rings a bell. It says, "The vessel management system is supposed to issue audible alerts of potential dangers, but as the Guardian neared the Tubbataha Reef before grounding, the Navy report said watchstanders on the bridge and in the combat information center did not report any alarms."

    I'm sure you remember the grounding of the USS Port Royal right off the international airport on Oahu in 2009. In that case, there was some talk about alarms from the vessel management system being turned OFF. Apparently that system, as installed, produces so many pointless alarms that crews were in the habit of turning the volume down (or whatever is equivalent that disables the alarms). That's an important interface issue for software systems that monitor safety: if it's too annoying, it's useless. Then again, from a different point of view, don't render your safety systems useless by giving the crew a mute button!

    -FER

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