Of RCOs and Radar


Well-Known Member
I have a few questions for anyone who knows the technical aspects of the ARTCC system.

Salt Lake ARTCC (or any Center) covers quite a large chunk of airspace. Is there just one radar site or are there many covering the area all transmitting data to the facility in SLC? What about the communications? I know they have different antennas spread about the country. How are they "hooked" the facility? Is it via landline or "beamed" via airways?
Hey SkyWChris,

From what I understand, there are numerous radar sites transmitting data to the facility. Communications between controllers and pilots are via the airwaves, while coordination between controllers in the same and adjacent facilities are through the landlines. At each sector, the controllers have a small screen with numerous touchscreen buttons. Each button connects the controller to a different sector. By pushing the button, the controller is in contact with another controller and they can coordinate with each other (the pilots never hear anything). Often times when you call a controller and he does not respond, or if you make a request and he gives you a "standby," he is on the "line," coordinating with another controller. Hope this helps!
Hiya Chris,

Most ARTCC systems use what is called a "mosaic" system. That is, there are several radar sites that feed into the system, and then the ATC computers digitize and then create the displays based on the combined information. Most center radar updates about once every 6 seconds, while terminal radar is faster (once per second or so, depending on the system).

Most terminal radar is single site, although NYC has a mosaic (a complicated custom deal from a while ago), and some of the new combined facilities also have multiple sites (a new type of system, one in LA and other in DCA).

Lately, some facilities have gotten remote sites. Charlottesville in VA used to be controlled by Washington Ctr, and it was a real PITA to get into and out of when it was IFR because of separation requirements and radar coverage. A few years ago, some other facility got a new ASR-9 radar, and then they took the old system and put it on a hill next to CHO and remoted it to Richmond Approach. It was a HUGE improvement.

The radio network is the same deal. Most freqs have a primary and a backup tranciever, and there are numerous sites all over the center's area of coverage. Every once in a while you will hear a controller tell someone to try another freq that they give them improved reception via another location. I know in Montana SLC center had remotes at the busier airports that were uncontrolled or when the tower closed. MSP center had the same deal with some NoDak and SoDak sites.

In both cases, land lines and microwave is used to connect the remote sites to the main facility, depending on geography and local service.

Very best,
Wow, great posts, guys, thanks! Yeah, I've heard, the "sorry, on the landline." I've been tempted to use that one when I've missed a radio call- but I chicken out every time. Don't want to get on ATC's bad side (Skywest, turn right 30-degrees, slow to 250).
I thought about saying that too, but I fear: "Delta 1491, descent and maintain 17,000 squawk 1200 frequency change approved"