ATC Radar Question

and that has nothing to do with Mode C accuracy

"Matt Barrow" wrote in message
...
"Stealth Pilot" wrote in message
...
On Fri, 12 Jun 2009 03:54:29 +0000 (UTC), Clark
wrote:

Jackie wrote in
:

[snip]

Does precision approach radar require a transponder to report altitude?

PAR uses a height finder radar to provide sufficient vertical resolution
for
precision approaches.

Mode C only provides 100 foot altitude resolution. bzzzzt!

Mode C provides a height eg 1252ft which is deemed only accurate to
100ft because the calibration errors are limited to 100ft.

And when local BARO is not available, the minimums go up.

And why the slop (calibration error) is taken into account when developing
the
approach procedure.