Appropriate action...

[HRutila]

In this circumstance there was nothing the controller could do. We had 5 in the pattern with an additional 4 or so inbound to land, so they were busy. (This is pretty typical at KLAF.) I was conducting a touch and go in a Skyhawk. Once I departed, a Cirrus was cleared for takeoff behind me. I watched him in the rear window while my student was climbing on upwind. Spacing looked fine then.

A normal pattern calls for turns to be made within 300 feet of pattern altitude. The Cirrus pilot turned early, and while conducting his turn from crosswind to downwind, almost hit us while we were making the same turn. The Cirrus was faster and therefore had a wider turning radius. With his wings up and belly facing our windscreen, he could not see us. It was an honest mistake.

The FAA determined there was roughly 150 feet of separation. How they determined that, I have no idea. We are one of few Class Ds that don't have a radar display. (Most do.) The nearby approach control's radar can pick up targets at around 2,500 feet MSL, but our pattern altitude is 900 feet lower than that.

It's not always a matter of the tower controller pulling tricks out of a hat. No 360, downwind or upwind extension would have resolved it. I don't even think a tower radar display would have helped because it's not an effective pattern management tool. To the controllers' credit, they do an excellent job without one. Our peak days see 600-900 ops a day.

[awreaper]

We are one of few Class Ds that don't have a radar display. (Most do.)

I was under the impression that it was the opposite, that most class D (not TRSA) facilities lack radar. There are several class D airports around my area and I know of none that have radar. The C and B of course do.

[Kyle.Sanders]

I may be wrong but I think those deltas that are close to TRACON facilities get remote feeds from that TRACON. For example- KSMO.

But something like KGCN won't have radar.

Regardless, they only use it as an "assistant", not for radar services.

[HRutila]

We are one of few Class Ds that don't have a radar display. (Most do.)

I was under the impression that it was the opposite, that most class D (not TRSA) facilities lack radar. There are several class D airports around my area and I know of none that have radar. The C and B of course do.

From a pilot's perspective, it's not usually discernible through the typical radio exchanges whether or not the tower has a radar display. There is also a big difference in terms of what the tower can do with that display. (Most cannot say "radar contact" or apply separation, but can use it for reference purposes.)

According to FAA OPSNET, of the 130 towers operated by the FAA, there are only 3 that do not have radar: Lafayette, IN (LAF), Helena, MT (HLN), and Twin Falls, ID (TWF). HLN and TWF both have non-radar approach controls as well.

There are several federal, state, and local government contractors (and even some contractors for private entities) who operate an additional 253 towers in the U.S. and its territories (Contract Tower Association Newsletter, Dec 2015). I don't have a stat to back this assertion, but at least half likely have a radar display.

[awreaper]

According to FAA OPSNET, of the 130 towers operated by the FAA, there are only 3 that do not have radar: Lafayette, IN (LAF), Helena, MT (HLN), and Twin Falls, ID (TWF). HLN and TWF both have non-radar approach controls as well.

There are several federal, state, and local government contractors (and even some contractors for private entities) who operate an additional 253 towers in the U.S. and its territories (Contract Tower Association Newsletter, Dec 2015). I don't have a stat to back this assertion, but at least half likely have a radar display.

Interesting and good info. I took a tower visit at our local Class D a couple of years ago and they didn't have radar that I noticed. They are not in the list of 3 but they very well may be in the list of 253.

[HRutila]

Update: Just got some new stats. There are 313 towers with radar in the U.S. There used to be 312 up until today when LAF finally received one.