Fighter Jets distorting GPSreading?

[Mulf]

I was out on the Chester River just before noon today motoring approximately due west toward and about to enter the channel into my marina when two fighter jets approached from the east flying low and headed west towards Annapolis. I had already checked my chart plotter and it showed my boat headed perfectly into the channel for the marina. I looked up at the jets as they thundered over me and when I looked down at the chart plotter again my boat had moved a quarter mile south on the plotter and was still on the same westward heading which meant it showed headed for the beach. As the two jets got further away the boat on the plotter which was still tracking westward parrallel to my actual course drove right up on shore, and across the parking lot while also moving sideways/northward through the marina clubhouse and finally back to and eventually lined up right down the middle of the channel where the real boat actually was. Has anyone else ever heard of or had this happen to them? Can the fighter jets deliberately throw off the GPS like that? Thank goodness it was daylight and I was navigating visually or I would have been calling Boat US to get my boat off the beach.

 

[abe]

Get it straght...GPS for GOVERNMENT MILITARY USE

ONLY!!!!!!!!!!!!!!!!!!!!!!!. Civilian use is a gift not a right. If its at night and the military shuts off the GPS, its your problem not theirs.abe

 

[Chuck]

Airlines

Hope the airlines understand this.lol

 

[HueyDr]

Good rumor though.......

Interesting gesture, but like the black helocopters, not true. Although the military has the ability to degrade GPS signals, individual aircraft do not have that capability. Rather than your coarse moving, you actually would see a loss of signal if the aircraft someway interfered with the signal.This from a black ops pilot.....we weren't spying, just lost

 

[abe]

Airlines do understand...they don't just rely on

GPS...get educated guys.

 

[abe]

Sorry, but my beef is...................

if 1. the original poster wants to blame the government for somehow disrupting his/her GPS....well again GPS is for the military NOT civilian use. We civilians tap into it (in fact the whole world taps into it) and not pay anything to the USA 2. never rely on technology only to get you from point A to point B. If your boat ends up on the shore because the GPS was turned off, no different then if your GPS unit burns out...your fault.abe

 

[Jo]

Airlines and GPS

Airlines dont rely GPS? News to me. Oh well, I'd better call my chief pilot ASAP and let him know. Lotta folks out there bustin rules... Please dont tell the FAA.In response to the first post. It sounds as though your GPS may have gone into "Memory" mode due to degraded satellite reception. Some GPS units will continue "Dead Reconing" position for a certain period of time if they are not receiving sufficient satellite signals, but are otherwise functioning. If you initiate a turn during this process, it will display your position inacurrately. Cause? Who knows. But certainly not jamming from a couple of fighters.

 

[Anon]

Oh this gov'ment thing again

who exactly are they ?

 

[RAD]

Oh this gov'ment thing again

You know "Them" ;D

 

[abe]

Jo, ignorance is a blessing

gee, I wonder how they got from a to be before gps....that system is still alive, I don't mean looking up in the stars either. You really think, that if GPS goes down your airline pilots can't navigate? WOW.abe

 

[abe]

Anyone here ever heard of LORAN before GPS..

it is still in use sometimes primary most of the time as a secondary system. It is still alive. Military can change GPS satellite anytime they want to confuse missles that use GPS for guidance...the Iraquis found that out when the Chinese sold them a bunch of GPS jamming systems. I guess for some people here they have never heard of pencil and paper balancing their checkbooks nor the day when PCs did not exist. ALL pilots know that in case of war they can not depend on their GPS systems... LORAN and other systems are used as back up. abe

 

[Mulf]

Jo: Thanks for the only

logical possible explanation to my honest question. This really happened, perhaps coincidental to the jets as some suggest, but most of the replies are very antagonistic and not at all helpful. You were the one out of 10 tried to help. My thanks, Mulf

 

[Don12364]

Chart Datum?

Mulf,Seems unlikely that passing aircraft can distort/modify GPS timing. They could blot out your reception by transmitting interference but then your GPS would simply freeze at its last good position. Also I don't see any purpose in transmitting false positions from fast moving aircraft as missiles would not use GPS to hit them.If you were using corrections from a ground station these could have been modified.I just wonder if your plotter changed charts and the new chart was drawn on a different datum to that which your GPS is set. I had this effect several times this summer whilst navigating the canals in the Netherlands.However, if it has been okay when you have been in this same position previously then it probably is not datum shift either.May I suggest you watch it carefully on the next trip and let us know please.Regards,

 

[Ross]

Just check out this link

http://tycho.usno.navy.mil/gpsinfo.html

 

[Clyde]

GPS Interference

Instead of looking up, you should have looked at the boats within 2,000 feet of you. It's been reported that certain types of powered Marine TV antenna will cause GPS interference due to an amplifier malfunction in the powered Marine TV antenna unit. The Radio Frequency (RF) interference has been reported up to 2,000 feet away on other vessels using their GPS unit. The GPS interference symptoms"...caused the position of the vessel as displayed on the electronic chart to move erratically and dramatically often across large expanses of land. As can be expected, various data displays indicated erroneous information such as excessive speeds."Most likely it was some boater watching his TV instead of the jets flying overhead. It was only a coincidence that the GPS interference occurred while the jet were flying near you. Any radio based system can be jammed, it doesn't have to be on purpose.Fair Winds,ClydeSAFETY ALERT - TELEVISION ANTENNAE INTERFERENCE WITH GPS http://www.uscg.mil/hq/gm/moa/docs/11-02.htm

 

[Ben16737]

Signals can be scrambled

I know that GPS signals can be scrambled/blocked, but I would imagine that it would simply freeze up your position on the chartplotter, not that it would report an inaccurate position (as some others already mentioned). Anything's possible, though, and I'm no expert.I'm glad the responses started to get a little bit lighter towards Mulf. I don't think he was implying that the GPS system is for the benefit of boaters or that the military should cater to him, he just wondered what was going on.

 

[Cathy]

yes, but

The gov't can scramble the signal whenever they want, but I doubt the jets did it. They are currently repositioning the satelites so east coast coverage may not be as good as usual for the next year or so.

 

[Kaizen]

Loran

Guess who runs LORAN. You can'r trust anyone. Take a look at the stars. Unless his almighty trying fool you, the stars are your best bet.

 

[Ross]

Kaizen, Guess who sets the time and prints the

almanacs? If we aren't careful we may be going back to latitude sailing.

 

[catwithhat]

GPS scramble

I've seen my GPS go gaga when sailing close to Widbey Island Air Base.. I had wondered about the possibility that they might scramble the signal.