Question

Which statement is not correct for GPS?

• A. It does not work in tunnels.
• B. It does not work underwater.
• C. It gives coordinates in local datum.
• D. It gives ellipsoidal heights.

Hint:

GPS uses WGS84 — a global datum, not a local one.

Answer 1

The Correct Option is C

GPS works by receiving signals from satellites, which cannot penetrate solid structures or water.
So, it indeed does not work reliably in tunnels or underwater — statements (A) and (B) are correct.
GPS calculates positions in a global reference frame, usually the WGS84 datum, which is a global geodetic datum, not a local one.
Local datums require transformation from the global coordinates.
Also, GPS provides ellipsoidal heights based on the reference ellipsoid.
Therefore, the incorrect statement is option (C) — GPS does not give coordinates in local datum by default.