"Squawk standby in the pattern"

[roncachamp]

I wish I could give you a list but I know I've heard of them over the years. Here is an article about a tower and it mentions they have secondary radar only:
http://www.maldivianairtaxi.com/int...-at-atc&catid=42:flight-ops-general&Itemid=53

Do you know of any in the US?

It's a fairly common thing I believe. I imagine it might be cheaper to build out secondary-only versus primary?

Why do you believe it's a fairly common thing?

 

[roncachamp]

I don't think it was a matter of too much stuff on controllers' radar screens - I think it was a matter of the radar not even being able to handle that number of transponder replies in that small of an area. Somewhat similar to how everyone is supposed to turn their DME off while on the ground at ORD - It simply can't handle the sheer number of requests and replies.

That's pretty much the case. The scope would seem to pulsate, could be quite distracting.