People screw up. Period. The Costa Concordia, that Talgo train driver in Spain, pilots fly into the ground as in San Francisco, just to name a few.
IMO, putting all one's eggs in the GPS basket is simply foolish, especially when a continuous cross-check with an independant nav system can be implemented, probably for lest cost than a dinner at the Captain's Table. I was a guest on the bridge of a ship as it went through the Straights of Gibralter and the Captain was using RADAR, Peloris sights, and multiple lookouts. Suspenders and a belt. The modern supertankers and container ships probably don't do that. The highly automated ships don't carry a lot of crew. -John ================= > As a (former) Naval Officer, I will tell you that a competent mariner > should always be using and cross-checking /all /sources -- GPS, radar, > dead reconing, /looking out the window/, and even celestial in open ocean. > > (I frequently had to remind my junior officers that nobody ever ran > aground or collided with another ship from spending too much time > looking out the window. Way too easy to get their heads stuck in the > radar or the GPS map. > > 73, > Jim > wb4...@amsat.org > > On 7/27/2013 9:43 AM, Scott McGrath wrote: >> Key here is how does the captain know that GPS is no longer providing an >> accurate fix? You need 2 or more independent systems to cross check >> each other. >> >> Sent from my iPhone >> >> On Jul 27, 2013, at 12:21 AM, Jim Lux <jim...@earthlink.net> wrote: >> >>> On 7/26/13 8:45 PM, J. Forster wrote: >>>> I gather from the article, the GPS position was spoofed and the >>>> autopilot, >>>> in bringing it back to where it was supposed to be, actually took it >>>> off >>>> course. >>>> >>>> There are places where a few hundred feet makes a big difference, viz. >>>> the >>>> Costa Concordia. >>>> >>>> IMO, this is a very convincing reason for something like LORAN. >>> I think it's a convincing argument for a captain who pays attention to >>> the other navigation instruments and doesn't blindly follow the GPS. >>> >>> It's also a convincing argument that shipboard >>> automation/autopilot/autocontrol vendors need to make more >>> sophisticated software (which I suspect they do, particularly on 200+ >>> foot ships.. I would imagine that there are some aspects of this demo >>> that are contrived.) The ship making and driving business is pretty >>> unregulated. It's all about what the owner of the ship is willing to >>> pay (or what he needs to get liability insurance, if he wants). >>> There's nothing even remotely like DO-178 for shipboard stuff. >>> >>> The folks doing stabilized oil rigs probably have sophisticated >>> systems, but they're also using IMUs and other stuff. Ditto for high >>> value things (oil tankers, warships). Molasses tankers? They're >>> probably lucky to have a functioning compass and some old charts. >>> >>> >>> I'm not sure, though, that looking at the big picture, whether your tax >>> dollars are better spent on LORAN, or on some other precision >>> navigation method or on making jam resistant GPS receivers (which do, >>> in fact exist, and make use of things like direction of arrival of the >>> signal..) >>> >>> Note that a GPS system with 3 antennas (as is common in systems that >>> use GPS to derive attitude/orientation) would be extremely difficult to >>> spoof, and would be VERY inexpensive to implement. Either the carrier >>> phases and code phases are consistent for all the received signals or >>> they're not. A jamming signal coming from the wrong direction will not >>> have the right direction of arrival relative to the platform >>> orientation. One wrong signal might be tolerable (multipath, etc.) but >>> with a multi satellite fix, I suspect it would be hard to do it. >>> >>> Sure, one could throw up N pseudolites on a bunch of UAVs, etc., but >>> that's getting to be a bit noticeable. >>> >>> >>> For what it's worth, I don't know that LORAN has the performance to >>> avoid a Costa Concordia type foul up (assuming they were crazy enough >>> to do the near pass in the fog, so visual navigation didn't work) >>> >>> I seem to recall that LORAN had 1/4 nmi kinds of accuracy. it would >>> get you to the channel or mouth of the harbor, but not get you into >>> your berth. You might be familiar with the local propagation anomalies >>> and get better accuracy with experience in your local waters. >>> >>> >>> >>> >>> >>> >>>> -John >>>> >>>> ================= >>>> >>>> >>>> >>>>> I boat? The backup is a competent captain. He'd see the compass >>>>> heading >>>>> move and quickly disengage the autopilot. I had a boat for years >>>>> I'd >>>>> notice a 5 degree change. Mine was a sailboat so I'd be more >>>>> sensitive to >>>>> heading changes than a power boater but still the human is the >>>>> backup. >>>>> >>>>> Most autopilots don't directly follow GPS, they use GPS to determine >>>>> a >>>>> heading, follow it then use GPS to detect drift and re-compute the >>>>> heading. >>>>> the heading would be held by a compass sensor in a low-cost setup >>>>> or in a >>>>> larger setup a lazer ring gyro backed up by a compass. So a >>>>> spoofed >>>>> GPS >>>>> would cause the autopilot to "think" there was a bigger crooswnd or >>>>> current >>>>> and make a bigger heading change. >>>>> >>>>> I bet you could hijack a drone not a manned vehicle the pilot is >>>>> trained >>>>> to >>>>> monitor the automation and he'd very quickly turn it off thinking it >>>>> was >>>>> broken. >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> On Fri, Jul 26, 2013 at 8:41 AM, J. Forster <j...@quikus.com> wrote: >>>>> >>>>>> Prof. Humphry from Texas just reported being able to spoof GPS in >>>>>> the >>>>>> Med >>>>>> and take over the nav system of a luxury yacht. He's done this >>>>>> before >>>>>> with >>>>>> a drone in the US. >>>>>> >>>>>> LORAN as a backup, at least? >>>>>> >>>>>> -John >>>>>> >>>>>> ============== >>>>>> >>>>>> >>>>>> >>>>>> _______________________________________________ >>>>>> time-nuts mailing list -- time-nuts@febo.com >>>>>> To unsubscribe, go to >>>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>>>> and follow the instructions there. >>>>> >>>>> >>>>> -- >>>>> >>>>> Chris Albertson >>>>> Redondo Beach, California >>>> >>>> _______________________________________________ >>>> time-nuts mailing list -- time-nuts@febo.com >>>> To unsubscribe, go to >>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>> and follow the instructions there. >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@febo.com >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
