On Feb 12, 5:57 pm, Ed Rasimus wrote:
On Mon, 12 Feb 2007 20:43:54 GMT, "Steven P. McNicoll"



wrote:

"Ed Rasimus" wrote in message
.. .

GCA = Ground Controlled Approach. PAR = Precision Approach Radar (A
GCA with both glide path and centerline guidance. ASR = Air
Surveillance Radar (A GCA with centerline guidance only, using
recommended minimum altitudes at various ranges from touchdown)

Both ASR and PAR are GCA.

A surveillance approach does not necessarily include recommended minimum
altitudes.

Terminology and precision in language again. An ASR has minimum
altitudes and a "begin descent" point after which you can descend to
minimums as fast or as slowly as you choose while being guaranteed
terrain clearance. My insertion of the modifier "recommended" was bad.


Our controller terminology was "X miles from runway" and "descend to
your minimum descent altitude". The controller provided course
trending information and the pilot was expected to maintain separation
from terrain. Recommended altitudes could be provided on final
approach if the pilot requested. The armed services may/may not have
slightly different methods on altitude information.

One other difference between a PAR approach and an ASR approach is
that in the PAR approach the distances as given are from touchdown,
and in the ASR approach distances are from the runway.

John Hairell