GPS altitude again is close to actual

Mxsmanic wrote:
writes:

You don't understand how WAAS works.

Yes, I do. There are only 29 reference points in WAAS, including
Alaska. The corrections are completely accurate for these surveyed
reference points. For all other points, the corrections are
extrapolations.

You don't understand how WAAS works.

The corrections are to grid points based on observables from multiple
reference stations.

This is different from LAAS and many DGPS systems, which use local
reference points to develop corrections for local receivers. No
significant extrapolation is required, so potential accuracy is
higher.

This is false. Being inside the reference network is all that matters,
proxitimity to a WRS does not matter.

No. The exact conditions of atmospheric disturbances and other
sources of inaccuracy cannot be fully predicted on the basis of
non-local references. The only truly accurate way to get this
information is to measure it at the point where it will be used.
However, this is very expensive, which is why WAAS was developed. It
trades a slight loss of accuracy for much lower cost.

You don't understand how WAAS works.

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