Controllers need to stay current, too. At least when it comes to guiding pilots down an ASR (airport surveillance radar) approach. Twice in the past two weeks the controllers at my home airport at Muskegon, Michigan asked me if I would fly an ASR approach to help them stay sharp and current. Of course, I would be happy to.
During an ASR approach controllers watch their radar and transmit an almost continuous stream of course corrections to keep a pilot lined up with the runway extended center line. ASR only provides lateral guidance so controllers can only tell you if you are left, right or correcting relative to centerline. For descent they tell you the minimum altitude, and then also tell you at what point to begin descending to that minimum.
Precision approach radar (PAR) has a vertical component and controllers actually “vector” you down the glidepath as well as along the extended centerline. PAR was never very common in civilian flying, but was the norm for precision military approaches for many years. I never got to fly a PAR for real, but I can understand how military pilots—particularly in single seaters with that huge workload—loved that voice in the headset telling you exactly how to find the runway.
The ASR approaches are still available at airports where there is, obviously, radar approach control. But not all airports with radar service offer ASR. I remember several years ago while I was based at White Plains, New York, we lost our ASR because the radar controllers moved from the tower to what was then called the “common IFR room” over on Long Island.
The “common I” as it was called back then, grew into the TRACON (terminal radar control) where controllers use radar to vector airplanes to and from several airports. At Muskegon we have an ATCT/TRACON which stands for air traffic control tower/terminal radar control. The fact that the radar is a single site on the Muskegon airport, and that the controllers are in the tower on the airport, is what apparently allows us to have ASR approaches but they are not on the list of approaches over at the big airline airport in Detroit.
The first practice ASR I flew was a directional gyro functioning type. In other words, I had the ability to fly an assigned heading. This type of ASR would be crucial if the nav receivers, but not the com, in my airplane failed. Or if the approach aids on the ground were to fail. Obviously, having WAAS GPS onboard means there would need to be multiple failures to leave me without approach guidance, but still . . . .
The other type of ASR is a “no gyro” approach designed to get a pilot to the runway after he has lost his directional gyro, or both directional and attitude gyros. That kind of ASR guidance could be a lifesaver no matter how many navigation systems you have onboard because partial panel in the clouds is always an emergency.
The controller starts the ASR by telling you the minimum descent altitude, the missed approach procedure, and the maximum time between transmissions that will elapse. If that time is exceeded you must assume lost com and go missed.
It was blowing about 20 knots at my altitude during the ASR approach with heading vectors. You are supposed to make standard rate turns to the new assigned heading. I kept the heading mode of my KFC 200 autopilot system engaged and followed the flight director commands to each newly assigned heading. It was sort of close to standard rate, but the heading corrections were 10 degrees initially, and then 5 degrees on short final so the rate didn’t matter all that much.
I had the GPS LPV approach dialed up so I could see exactly how well the controller was doing with his vectors, but I didn’t cheat. I flew the assigned heading and it worked out great. By the time I was on very short final I was offset maybe the width of the runway, or about 150 feet. Good job by that controller.
For the no-gyro ASR all you hear from the controller are turn right or left, followed by stop turn. The initial intercept angle was pretty steep and it was odd to hear “start turn” and many seconds before “stop turn” put me on the intercept course. This time the wind was 24 knots almost directly across the final approach course so the controller really had his work cut out for him.
I wasn’t being all that helpful either. Early in the procedure I was indicating 175 knots because I had been a little late in getting down to the initial approach altitude. Once level I slowed to the 152 knot gear/approach flap speed, extended both, and then slowed to about 120 knots for the last couple of miles. The controller had to observe my path, issue turn instructions, while not knowing exactly what the wind was doing, and what the heck I was doing with big changes in speed.
On this approach I also used the flight director, but only to give me a bank angle target that I held until hearing the stop turn command. And the controller did a terrific job. His last instruction on about a quarter mile final had me about two runway widths to the right and correcting back to centerline. With the minimum visibility requirement of one mile I would have easily seen the runway.
With the FAA’s NextGen system in development and satellite guidance showing all of us exactly where we are all of the time the ASR will go the way of the four-course range one day. And it will be missed. Knowing there are controllers down there with the skill to “talk me in” if my worst day ever comes down to that is nice. And helping them—and me—stay current in the procedure is a great pleasure, and I hope that you, too, have the chance to fly an ASR before they’re gone. Ask approach control where ASR is available. There is a good chance they need and want the practice, and so do we.