Jim Logajan wrote:
Jackie wrote:
If an aircraft is at 18,000 ft (approx 3 nm) and 3 nm away from the
radar antenna, as seen on a map, how does the radar correct for slant
distance when distance is displayed (e.g. using concentric circle
distance markers on the scope or relative to a known distance, such as
a marker on the display)?

Without altitude information from the pilot or a Mode C transponder, the
radar system can't extract the horizontal distance from the slant distance.
Where did you read that their systems correct for altitude without Mode C
transponders?

I don't believe I indicated I read this.

If they could do that then they wouldn't have ever needed the
transponders to report altitude.

Does precision approach radar require a transponder to report altitude?