NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: A credible AIS track for the Costa Concordia
From: Lu Abel
Date: 2012 Jan 25, 14:09 -0800
From: Lu Abel
Date: 2012 Jan 25, 14:09 -0800
Frank:
Thanks for the info. The video is obviously of someone working on a screen. 'Twas late and I wanted to send it out and didn't have time to track back to the original (QPS).
It's interesting to view both -- QPS for a better plot, but GCaptain for comments like "turn the helm to starboard and the stern kicks to port" (not sure these were the exact words, but whatever they were exactly, they helped interpret the AIS track.
Not sure I totally agree with you on the "interpolation" comment -- the QPS display shows the AIS data being updated every five seconds. I suspect things happen slowly enough on a large ship that straight-line interpolation
between the data points is very reasonable.
What I find fascinating is vessel position and track versus vessel orientation (taken, presumably, from its gyrocompass). So we can see the Costa Concordia rotate, but it takes a distinct amount of time before its course agrees with its orientation. And it's final flailing off the port is especially fascinating.
Lu Abel
From: Frank Reed <FrankReed@HistoricalAtlas.com>
To: NavList@fer3.com
Sent: Tuesday, January 24, 2012 12:10 AM
Subject: [NavList] Re: A credible AIS track for the Costa Concordia
It's a plausible and consistent story, but we still have a bit of smoke and mirrors here. That looks like it's AIS data, but it's not pure data. There is a limited amount of AIS data that became available right after the incident, but it has big holes in it. Is this video interpolating between those "big holes" with best guess positions? If you look closely under the video at gcaptain.com, there is a small notice: "AIS data via QPS Maritime Software" and if you follow that link, you will find that the video shown at gcaptain.com is actually from QPS: http://www.qps.nl/display/qastor/2012/01/17/20120117_stranding. Konrad at gcaptain.com is simply talking over their video (which is displayed cropped in a rather annoying fashion in the gcaptain version). On the QPS site they state clearly that their video was created with interpolated positions, but they don't describe that process or include the extent of the interpolation. The videos, however, are very nice, and they do fit the available evidence quite well. More troubling, if you look at their pdf document describing the grounding, it reads like an advertisement for their software and their "grounding avoidance" algorithms. Again, they do not explain the interpolation process (at least I could not find any explanation). Do these folks make the software which was, in fact, deployed on the Costa Concordia? Did they produce this reconstruction using position data which is available to them internally?The earlier supposed AIS track which was posted on a Turkish maritime news web site showing a track through that narrow, shallow gap between two little islands was almost certainly a hoax. And in fact the perpetrators were probably paid a nice sum for their fake track. It was quickly pulled without explanation from a few other sites which had re-posted it. In a similar hoaxing incident, Italian news media were slammed for repeatedly replaying a youtube video of panicked passengers that someone had sold them. It was labeled and sold as video taken on-board the Costa Concordia during the incident but it later turned out that it was taken during some cruise ship emergency a couple of years ago in the Pacific.Anyway, I think the story that has come together is a fairly simple one. The captain was navigating visually. He knew the area well and had made close passes before. He turned too late and hit the outer edge of the reef. The rest is history, and it's just amazingly lucky that the loss of life was not vastly greater. But how can one individual, fallible as all mortals, be the sole cause of this? Were there no other officers monitoring the vessel's position? Were there no automated systems warning of dangerously shallow water? Where was the backup to this fallible individual??The disinformation that has accompanied this story serves as a reminder: when entering the Internet, set your Nonsense Detector to MAXIMUM.-FER
----------------------------------------------------------------
NavList message boards and member settings: www.fer3.com/NavList
Members may optionally receive posts by email.
To cancel email delivery, send a message to NoMail[at]fer3.com
----------------------------------------------------------------
