Altitude Accuracy Question.

[+Eric K]

I was driving through the mountains of WV lately and there was a sign at the top of one of the mountains where it was something like 3252 feet.

 

My GPS said I was at about 3232 feet.

 

Which may be more accurate and would the fact that I was doing about 75 MPH at the time have anything to do with it?

Edited February 10, 2004 by Eric K

[+Stunod]

Elevation error is usually 3 times what horizontal position error is. Sounds like you had a pretty good reading.

[Radman Forever]

I think the GPS systems are more accurate. I always like to determine if road signs are really telling the truth about how far a place is, AND THEY ARE ALWAYS WRONG AND MY GPS IS ALWAYS RIGHT!

 

[Hogarth]

I was at the top of a ridge. The sign said x number of feet. The GPS Said Y number of feet. If I added the # of ft I was above the ground, the GPS was dead on. Edited February 10, 2004 by Hogarth

[+Naefearjustbeer]

I was standing on the beach at High tide mark and my GPS said -50 foot, I was still breathing air so I think the gps was out!

[+harleycache]

I was standing on the beach at High tide mark and my GPS said -50 foot, I was still breathing air so I think the gps was out!

Yeah, but you had a tank with 3000 psi on your back, and a regulator in your mouth!

[+Imajika]

The Legend has a feature that will let you correct elevation. If you are at a spot where the elevation is posted on a sign or something, you can manually correct the elevation listed on your GPS. The Legend instruction manual says it helps make elevation readings more accurate. I guess most Garmin models have this feature...don't know about Mags.

[+Markwell]

I actually called the Garmin PR department about this a while back. If the unit does not have a barometric altimeter, the vertical readings can be hundreds of feet off. Of course, just like any other reading on the GPS, the 3 dimensional position increases in accuracy with a better satellite constellation (three or more at wide angles close to the horizon are best).

 

If your unit does have a barometric altimeter, it needs to be calibrated for accurate readings. You need to have a known spot like a vertical control benchmark and set it EACH DAY you are interested in getting altitude readings.

 

It's gonna get you in the ballpark, but the GPS is NOT an accurate altimeter by itself.

[+gallahad]

...It's gonna get you in the ballpark, but the GPS is NOT an accurate altimeter by itself.

Moral of the story. Don't use it for instrument landings in bad weather.