Originally Posted by
Looigi
Not true. Pressure altimeters in Garmin units are subject to drift. What altitude correction does is adjusts the altimeter's data by matching it up to topographic data in the website's map database along the route. You might see this on a ride where you return to where you started and the raw data shows different elevations at the start and end of the ride. Applying correction will remove this error.
It's off by default for units with barometers.
It really exists for units which only use GPS for elevation (which is inaccurate).
There is no indication that it's useful for "drift" at all.
If drift was a general problem
and the correction was useful in fixing it, it would not be off by default (it would be on by default).
People are naively thinking that something called a "correction" is always good. In this case, it makes the GPS data better and the barometeric data worse.
Understanding Sport Device GPS Elevation Issues | DC Rainmaker
Note that Garmin Connect will automatically set the elevation correction to ‘Disabled’ for devices that have barometric altimeters, such as the Edge 500:
In general, if you want the most accurate elevation data you can get, you’re going to have to go with the Edge 500 or Edge 705 devices. But if you want portability and versatility, you’re probably better off sticking with the Forerunner line and then correcting the elevation later on the computer.
(Note that dcrainmaker talking about getting accurate elevation for units without barometers.)