"Roy Smith" wrote in message
...
In article ,
"Gene Whitt" wrote:

[snip]

I don't think the certification of what a controller can do with a brite
scope has much to do with where the antenna is.

Correct.

[snip some stuff about ops in NY that illustrate some of the various ways a
tower radar display may be used as well as the relationships between
non-approach control towers and their parent TRACON]

The problem is that some of the tower people become reliant upon
a radar screen that has inherent weaknesses and errors. The visual
skills of the past become less required and proficient. The position
reporting skills of the pilot become more important.

This certainly seems to be the case at HPN. I've had the tower refuse
to allow VFR pattern work because the radar was down. Or limit the
pattern to one or two aircraft. At CDW (in the pre-brite days), they
used to routinely handle 8 guys in the pattern and still work arrivals
and departures on both runways.

Part of this may depend on the level of radar service being provided at the
airport as well as local SOPs that are written with radar in mind.

But part of it can also be ascribed to a lack of proficiency amongst some
current local controllers. I'm sure there are still some who can work three
simultaneous VFR patterns along with IFR arrivals, departures, practice
approaches, and VFR overflights. I'm equally sure there are some who can't.

By the way, back when I was working I had to get up for a dayshift a week
ahead of time, eat a breakfast of cold gravel, walk barefoot through the
snow to get to the tower (uphill both ways), and strike flint on steel to
get the light gun started ;-P

A week ago I was with a student in a C-172 where we made a call-up
saying
that we were planning on a 45 endtry to the downwind. Immediately
afterwards a twin Commander made the same call. Neither aircraft was
able
to find the other and the controller could not distinguish one from the
other since both were squawking 1200. The difficulty arose from the
perception of what constitutes a 45 entry. The Commander was closer to a
direct entry to downwind than a 45.

One of the things I try to impress on students is that the tower at a
Class D airport has no responsibility for separating VFR from VFR in the
air. Most pilots seem to think that the tower is doing more for them
than they really are.

Alas, too true. See immediately below

In theory, the controller in your case could have said, "172, maintain
at or below 1000, break, Twin Commander maintain at or above 1200,
report the 172 in sight". That would have ensured you wouldn't swap
paint. But, I'm sure it would have also broken the rules the controller
operates under, so it'll never happen.

As you've already noted, the controller does not (some might even say
cannot) provide separation service to VFR aircraft outside Class B and C
airspace.

I can't envision why a controller would want to issue a restriction without
first knowing both aircraft's position and altitude. Otherwise he may only
make the situation worse by requiring one aircraft to climb or descend
through the other aircraft's altitude and/or flight path.

Plus, given the allowable differences in altimeter readings between the two
aircraft I'm not sure what good a mere 200ft would accomplish? If anything
500ft but again in Class D it's See and Avoid.

Better for the tower to issue traffic as they are required to do and for all
three parties to look out the windows.