Thursday, June 22, 2006

Shooting a GPS Approach at Flint

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If you wish, you can follow along on the approach using the approach plate available at the link below.

Approach plate for RNAV (GPS) Runway 36 at Flint Bishop International Airport

More information about US terminal procedures is available at the following link.

FAA - Aviation System Standards - Main Page for US Terminal Procedures

As regular Airspeed listeners are no doubt aware, I’m training for my instrument rating. For those non-pilots out there, an instrument rating essentially qualifies a pilot to fly an aircraft without looking out the window – To fly solely by reference to instruments. To simulate those conditions on nice days, I fly with a view-limiting device that attaches to my headset. At about 400 feet off the ground, I flip it down and I can only see the instruments in front of me. Sure, I could cheat a little if I wanted to (it’s hard not to catch a glimpse out the front window when you look at the magnetic compass up on the dash), but I expect to go fly in the clouds for real once I get the rating, and I really need to learn this without sneaking peeks.

Anyway, I thought I’d take you along on a flight so you could get a better understanding of one of the most crucial aspects of instrument flight, and that’s communication with Air Traffic Control or “ATC.”

Air traffic controllers are some of the most talented people with whom I interact. Bear in mind that I interact with some of the smartest people in the country on a daily basis as a technology and aerospace lawyer, so when I say that ATC personnel are special, I’m really saying something. I talk to at least a half dozen on each flight. They’re ground controllers, tower operators, approach and departure controllers, center controllers, and others. Each does a special job that bears on a different phase of flight.

The flight today is a standard training flight as I prepare for my Stage Three check flight as part of the Part 141 program at Tradewinds Aviation at the Oakland County International Airport just outside of Pontiac, Michigan. The airport is called “Pontiac,” even though it’s located in Waterford, and I tell you this because you’re going to hear me call it that on radio calls.

We’re going to take off from Pontiac and then fly about 30 miles north to Flint Bishop International Airport. On this particular day, we shot a total of five approaches. An approach is a way of navigating an airplane to a runway to land without being able to see out the windows until you’re very close to the runway. Many approaches will make it so that you can be in clouds and rain and other clag all the way until you’re 500 feet or so off the ground and a half mile from the runway. Believe me, that’s low and close.

You’re going to hear the first approach we did, which the “RNAV” approach to runway 36 at Flint. “RNAV” stands for “area navigation” and you fly RNAV approaches using GPS – the Global Positioning System. An RNAV approach is just one of about a half dozen different kinds of approaches that I have to know how to do.

Runway 36 is a strip of pavement that runs basically north-south. When you land on it going north, it’s Runway 36 (“36” meaning that the nearest ten-degree magnetic heading to the landing direction, which is 360 or 36 for short). That same strip of pavement is Runway 18 if you land on it going the other direction because your heading is roughly 180.

RNAV approaches usually look like the letter “T.” The runway is at the foot of the T. There are named waypoints at each end of the crossbar of the T and at the intersection of the lines of the T, as well as along the vertical part of the T. Because we’re inbound from the south, you have to turn the T upside down to visualize it on a map that has North at the top.

There’s a link to both the FAA’s Aviation System Standards office, which prepares the approach charts, as well as a link to the chart for the RNAV 36 approach in the show notes at We’ll repeat that link at the end of the show. Download it and follow along if you can.

Anyway, let’s go flying. We’ll start out sitting on the ground at Pontiac with the engine running. I have my view limiting device at the ready and my flight instructor is in the right seat. Ground control has cleared us up to a taxiway intersection near the departure end of the runway. I key the mike and call the tower to tell them that I’m ready to go.

[Audio 1]

I’m now cleared to pull up to the runway – but not onto it – and wait for clearance to take off. The tower controller is checking to see if the route I’m flying is clear and make sure that there will be room for me to land when I get to Flint.

Then it’s time to go.

[Audio 2]

Here’s the takeoff run. I self-brief the important airspeeds as the aircraft gets going and then call out the speeds up to rotation at 55 knots.

[Audio 3]

Very shortly after I get off the runway, the tower hands me off to a controller in Detroit who will control my progress to Flint. The tower controller does this over a land line to Detroit. Normally, I have to call up Detroit approach by saying something like “Detroit approach, Cessna Niner One Eight Tango Alpha, with you at one thousand five hundred climbing for three thousand.” But the approach controller is really on the ball today – or really busy and wants to get me going north as soon as possible. Here’s the handoff. Note how quickly this happens after I switch frequencies.

[Audio 4]

I’m “under the hood” now – I have pulled down my view limiting device and I’m completely on instruments.

After five or ten minutes, Detroit approach hands me off the Flint approach. The Flint approach controller will handle me until I get within about five or ten miles from the airport itself. I have filed an instrument flight plan that tells the Flint approach controller and tower that I’m going to do practice approaches. But they don’t know precisely what I want to do, so I need to tell them. The approach that we’re going to hear here is the first one for which I ask the Flint controller. I call it the GPS approach, but he uses the RNAV nomenclature, which is more proper. He clears me to a waypoint called FISKU, which is the eastern tip of the crossbar of the inverted “T.”

[Audio 5]

We’re getting closer. The controller tells me to descend from my present altitude of four thousand feet above sea level (or about three thousand feet off the ground) to three thousand feet above sea level (or about two thousand feet off the ground).

[Audio 6]

I’m approaching FISKU now and passing it. We approached FISKU heading almost due west and we’re supposed to fly a course of 275 degrees magnetic between FISKU and the next waypoint. The next waypoint is called HITMO and it’s at the intersection of the two lines of the T. A lot of self-talk here as I brief the approach out loud.

Approach clears me for the approach, which means that I can fly the approach all the way to the runway, but I’m not cleared yet to land. That will happen after approach hands me off to the tower controller.

[Audio 7]

Now the approach controller hands me off to the tower. I’m now past HITMO and on my way to JORDI, which is about halfway along the vertical part of the T. I’ve been stepping down my altitude here so that I arrive at the runway low enough to get down and land. I’m at 2,400 at HITMO. JORDI is the “final approach fix.” On this approach, it’s the place from which I can descend to 1,260 feet (or about 500 feet off the ground) and start looking for the runway so I can land.

[Audio 8]

The tower now clears me to land. “The option” means that I can land and stop on the runway, do a touch-and-go, go around, or shoot a missed approach. As a courtesy to the tower, I tell him that I want to do a missed approach. This has two functions. First, we only have about two hours to fly, so I don’t want to take the time to actually land and then take off again. I want to get to the point where I could land the plane if I wanted to, then go full throttle and then get on with the rest of the training maneuvers for the day. The other thing is that I want to fly the published missed approach. This is what I would do in practice if I got down low and the weather was bad enough that I couldn’t see the runway environment well enough to land. Each instrument approach has a missed approach procedure. In this case, it’s a straight climb north of the airport and then a right turn to hold at a point about 12 miles east of the airport called KATTY. The tower clears me, I tell him about the miss, he checks the airspace to the north and east of the airport to make sure that it’s clear and then tells me that I can expect the published miss.

[Audio 9]

So here’s the crucial part of the approach. You’ll hear me counting off the feet until we’re at the Minimum Descent Altitude of “MDA.” This is very important because there’s no outside vertical guidance on this approach. Just me looking at the altimeter and remembering how low I can go. If an instrument pilot obsesses about anything, it’s usually about the MDA. You don’t want to be low, because there might be antennas, buildings or innocent podcast listeners down there and you don’t want to hit any of those things. That would be rude and it upsets flight instructors and FAA officials alike.

Then I’m at 1,260 feet doing about 90 knots. If this was for real and I didn’t have a view limiting device on, I’d be dividing my scan between the instrument panel and out the window looking for the runway. As it is, I keep the view-limiting device on and fly it all the way to the missed approach point, then tell the tower that I’m going missed.

[Audio 10]

So I’ve gone missed. Full throttle and pull the nose up and get out of there. If this were for real, I’d be down low and flying blind, so it’s very important to get the heck up and out of the way of the aforesaid antenna farms, buildings, and podcast listeners. The tower hands me off to the departure controller (actually, the same guy that I earlier called “approach,” but I’m outbound now so I call him “departure”). I’m cleared for the published missed approach procedure and the controller gives me a time to expect further clearance.

[Audio 11]

That’s it. Did you notice how efficient the controllers were? How about Flint tower, which had two different people working – The woman who cleared me on the approach and then the man who handled the clearance for the option and the missed approach? How about their interaction coordinating the transition from approach to tower to departure? For 6that matter, how about Detroit Approach, where I didn’t even have to call him up?

What you didn’t hear much of was the other traffic and the other aircraft that all of these people were handling. It was a busy day at Flint. Airliners, training aircraft, and people further away that were getting flight following. ATC is made up of absolute professionals and I take my training very seriously because I need to be able to receive, understand, and execute the instructions they give me so that they can work me in to some really busy airspace.

Yes, there are surly controllers who will yell at you at the drop of a hat. There are also guys who occasionally don’t have their heads in the game. But those are definitely the exception rather than the rule. I really enjoy flying in the system and controllers like these really make me want to be worthy to be in their airspace. I can’t say enough about controllers in general, but I’m especially grateful to the controllers at Flint. Russ Chew, are you listening? These are first-class people, but I’m sure you already know that.

I should also note that I edited out several parts where I stuttered or had to ask a controller to repeat a clearance, as well as one point where the clearance got a little complex and I had to ask my instructor over in the right seat to acknowledge the clearance and scribble it down. But hey, it’s my show.

So that’s an instrument approach from takeoff to missed approach? Sound like fun? Stay tuned for more!

- Steve


Anonymous said...

Hey, I loved listening to your RNAV approach. It was great and I think new pilots would love to listen to it over and over again to get a feel for what it is really like in IFR conditions. My only problem was I could not pull up the approach plate. Might be my connection though. Not sure. I'm glad I found this site. Hope you keep it going!!

Anonymous said...

First comment was right on. As someone who's about to get his private and move on to instrument, I found it very helpful and entertaining. Thanks! However, I also could not retrieve the approach plate.