Hey- I still check outside and make sure I can see the cement plant and the water towers when I'm flying--- I don't totally trust that digital cockpit ya know. As a matter of fact, just last week we lost the air speed indicator for a while...I will be wearing my decoder ring when I take that FAA exam..

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"It's normal for these things to empty your wallet and break your heart in the process."
2012 SLK 350
1987 420 SEL

That's good to hear.

Wear the ring for sure. It might make a good ice breaker for you and the examiner. (Yes - I'm serious.)
If nothing else, joking about it may actually let him know you feel confident enough about your skills to even make a joke in the first place.

JD - No worries. The people boating around out in the world will be just fine.

(I'd explain, but I’ve just been informed that spending my entire life associated with aviation and working with GPS since it came out (civil), does not constitute actually knowing anything about it. That in fact, it’s just my ego that proclaims to. Guess I’ll have to find something else to do from here on out. )


Have fun this weekend Mistress.

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1980 300D - Veggie Burner !

I'm just passing along what I hear from the good folks at Cruising World

Understood.
I didn’t say they wouldn’t be effected.
I just can’t see it leaving someone in a boat lost at sea, or even into the rocks. Lest they use it for very tight harbor Nav, strict channel maneuvers or critical passage work.

Now the CAT-3 Airport and/or precision flight approaches systems and these Street Nav systems may be a whole ’nuther can of worms. We have recieved various FAA and Garmin GNS update information for some time now. It is an issue there, for sure.

Never had a street unit. Don't know.

Hatt would sure know more about the marine effects side of all this.
It just seems to me that the standard satellite non-WAAS enabled chart plotted systems have worked fine (Though not nearly as well of course.) for years at keeping folks in the know of their (basic) position. If you’re GPS is WAAS enabled, and looses the WAAS real-time correction function. Is it leaving the whole system out of commission? I’d hope not.

Hatt ???

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1980 300D - Veggie Burner !

For non-DoD, non-WAAS, non-subscription signal corrected systems you get about 15m accuracy. Even if SA were enabled you'd still get 100m accuracy.

Prior to GPS, any navigator on the planet would be well-pleased with 100m.

B

Well if you are used to a certain level of accuricy and suddenly lose it, you could be in trouble. Some harbors are extremely narrow, 20ft+/- can make the difference between going through or hitting the rocks. More so with larger commercial traffic.

I bet a few people have issues with this, weather or not it leads to accidents...is hard to say. To many variables.

As a side story a few weeks ago I was coming into Milford harbor at night with very poor visiablity. The GPS said we were not in the channel but I knew we were, and we were. If I had followed the GPS we would have been on the sand bar. Lucky for me I know that harbor like the back of my hand. If it was an unfamiler harbor I would have been following the GPS track.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Local conditions can affect the GPS solution. GPS receivers use the same algorithm for solution, though they may differ in the number of satellites from which they can derive solutions. But most use 8-12 satellites, though a useful solution is possible with as few as 4. The big difference in accuracy comes mainly from the filtering methods used to accept or reject a given satellite's data stream. Not surprisingly, that filtering comes at a price. The more you filter, the greater the precision and accuracy, and the longer it takes to capture enough data for a solution.

Installation of the antenna plays a critical role in solution accuracy. It should be as high as practical above your car or boat or aircraft and away from any reflective surfaces like walls or bulkheads or trees. This minimizes errors due to multipath reflections -- the signal dances on all surfaces and arrives at the antenna in slight time delays. If the time delay is shorter than your GPS's filter is capable of detection, the GPS will provide an inaccurate solution.

But if you demand extreme filtering to get say, centimeter accuracy, you wont get the solution in time to prevent your boat from running aground or your aircraft from slamming into the runway at 400 mph. But you will know exactly where you stopped.

B