Gig 601XL Builder writes:

Do you know of an aviation use of WAAS that isn't tied to GPS?

Absolutely. GPS can be used (and is used) for en-route navigation
without WAAS. It is more than precise enough for this purpose for
lateral navigation. Standard GPS can be used for any lateral
navigation except during take-off and landing, where it is not
reliable enough for safety as the sole means of navigation. Many
existing aviation GPS receivers do not include support for WAAS.

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