Study finds that a GPS outage would cost $1 billion per day

The study is likely to increase public calls for improved safety and security of the US GPS system, which the Air Force continues to modernize with its new fleet of GPS III satellites.

Bring Back Loran
all your GPS’s stop with a solar flare who needs made man disasters

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And subject to spoofing.

In 2016 Iranian forces captured two U.S. Navy boats that had strayed into Iran’s territorial waters. This was just after President Obama had succeeded in pressing that nation to give up nuclear weapons research, and was on the same day as Obama’s last State of the Union address. There was little reason for the U.S. Navy boats to have veered so far off course, and it was clear that the Iranian Navy was waiting for them.

Many speculated that Iran had spoofed GPS signals to lure the U.S. Navy boats into Iranian waters. U.S. officials have denied that this was the cause of the incident, but have not publicly offered an alternate explanation other than “mis-navigation.”

to spoof a plane you would need to be above it?

And the GPS system is still under US Military control.
Can it thus be made unavailable to other users at the wimse of the Commander in Chief. (??)

Scary thought. Think of all the confused drivers around the world that has become totally dependent on their GPS to find their way anywhere.
It will be more chaos on the roads than is already the case in many places.

Navigators on ships has access to alternative navigation satellite system.

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To some of us what a business opportunity. Dust off the trusty old sextant and sign up with a salvage company that worked on a share.

Not trying to rain on you parade but in the grand scheme of things, celestial nav is not out of the reach of most people if they are properly trained.

In these days you can probably get an app for your phone to work a sight so I agree in part. The problem that I observed is newbies don’t trust the position that they obtain if it differs from the position that they expected. Had a group of 6 cadets settled on a position on track and 5 miles to the west of my position, I was correct and reworking their sights they had position lines that agreed with my position but had agreed on position in their large cocked hat that was closest to the DR. After a background of recovering buoys in the Southern Ocean, ice navigation and time on tankers with no electronic position finding systems beyond DF, I knew when I stuffed up a shot and took another immediately and most importantly I trusted the position I obtained.

That’s about right, a cadet on the first time picking up a sextant will get within about five miles. On the second night with some adjustment maybe inside three miles, later with practice about two miles. The ship’s officers will do better from the start and improve faster.

That’s not bad, consider at sea passing another ship a 2 mile or more CPA is used.

We’ve had this discussion numerous times here but my question is how precise a position is needed? How much more accurate do fixes need to be to make radar landfall given a 48 mile radar range? Not to mention DRs, soundings and the like.

When relying upon GPS alone I stay more than five miles from navigation hazards because of possible chart errors from old surveys. If the celestial fixes are plotting poorly then it would be prudent to adjust the planned track-line for larger margins of error.


The problem isn’t location alone it’s integration and confusion.

This has happened to me while in the Bay Of Bengal during the start of the Iraq war.

When the problem started I was called up to the bridge and the watch officer and electronics technician (et) thought it was a computer problem. We had a go bag with a few abandon ship items including a small gps device. I fired it up on the bridge wing. Nothing. Then I told the et who’s began looking for interference.

My wife was aboard a preposition ship that had mysteriously gone “dark” a few days before so I thought I knew the answer but the et wasn’t buying it. So I got on the vhf and started calling nearby ships. After the third confirmed they had no gps the et was convinced.

That took maybe 15 or 20 minutes.

Then we had to dig through manuals and setting to find what equipment and features would be messed up.

It was a dp ship so the helm would be lost, or would it? AIS was down so forget that. Radar worked but some of the information panels were off. Was that information important? What else used gps to give additional information to various systems? Should we use our limited time to start doing a days work or focus maintaining a better watch.

Remember that ais we dismissed? Well it went into dead reckoning mode and one mate kept focusing on it and the wrong information it displayed despite me telling him not to.

Oh and then we remembered we had gps epirbs. Could they still locate us without gos signal?

We were offshore but what if we were in the singapore straight? Has VTS practiced a loss of gps scenario? How would the ships around us react?

The bottom line is there is a lot more to think about and this will only increase as more and more equipment integrates into the nmea stream.


I agree, that’s why worrying about getting ship’s position mid-ocean far from hazards and when workload is low is focusing on the wrong problem. There’s little navigation risk and plenty of time to sort things out.

When navigation is being done in restricted waters close to nav hazards and other ships is when both workload and risk is high

The bridge crew is going to have to quickly diagnose the problem and come up with a solution just when the resources needed to cope are at a minimum and precise navigation is most required.