by Charles Gulick
ILS That Flesh Is Heir To
To Snohomish County, Everett, WA
North: 21620. East: 6737. Altitude: 2200. Pitch: 0. Bank: 0.
Heading: 210. Airspeed: Cessna 114. Airspeed: Piper 122.
Throttle: Cessna 20479. Throttle: Piper 21463.
Rudder: 32767. Ailerons: 32767. Flaps: 0.
Elevators: Cessna 32767. Elevators: Piper 36863.
Time: 16:30. Season: 2. Cloud Layer 1: 4000, 900.
Surface Wind: 5 kn., 155 deg.
You didn't expect this weather, but it didn't expect you either, so you're even—almost. You were sightseeing, not paying that much attention to exactly where you were flying, but you know you're somewhere north of Seattle. The first thing to do in this situation is to slow down. That'll give you more time to think, and smooth out the turbulence a bit. So get into slowflight—immediately.
Next, find out how bad the situation is. Contact the Boeing tower on 127.75 and get a weather check.
Ceiling 800 feet.
800 feet! Or was that 900 feet?
Either way, it's big trouble. So think. There is one ILS (Instrument Landing System)—and one only—operable in the Seattle area. It's at Paine Field, in Snohomish County, and you had better use it. This is your chance to find out if your ILS localizer and glideslope really work. If they do, and everything else comes out all right, you'll have something to tell your grandchildren about. If they don't work, or everything else doesn't come out all right, or both, then … well, somebody else will have something to tell your grandchildren about.
But after all, you know how to fly this airplane, thanks to your rigorous training. Here you are in slowflight. You know how to control your altitude, how to make standard rate turns, and how to climb or descend at any rate you choose, using good old power. So get to it.
You need information—all of it you can get, so tune your NAV1 to Paine VOR on 114.2. (I'm giving you the frequency because I put you here, giving you no chance to get out the right chart.) Check your DME to see how far you are from the station.
Now do everything you've learned to do. Crank your OBS around and find out what TO radial you're on, then get inbound on that radial.
Next, be advised that an ILS approach works only when you're flying a specific radial, that is, when you're on one specific spoke—the spoke that's directly in line with the runway to which you'll be guided to land. To get the correct ILS runway, and the localizer frequency you're to tune for your ILS approach, use your COM radio and tune Snohomish ATIS (Automatic Terminal Information Service) on 128.65. If the information goes by too fast, call again until you have both the ILS runway to use and the localizer frequency.
Now, using your knowledge of how to change radials, get on the correct radial for your ILS approach. And as you fly toward it, tune your NAV1 to the ILS localizer frequency—not the OMNI frequency, but the localizer frequency ATIS just gave you. After that, tune your NAV2 to Paine VOR on 114.2 to track your progress over the radials.
Now the NAV1 OBI becomes the instrument of your focus. But this time you have not one but two needles to fly—the usual CDI (Course Deviation Indicator) you keep centered when tracking to a VOR station, and a new needle, which now appears at the top of the instrument, the glideslope. The glideslope is flown like the CDI, meaning you fly toward its needle in the same way you fly toward the CDI needle. But wait until the glideslope needle gets to the center of the OBI before you start correcting. Even though you're below the glideslope now, as you get closer to Snohomish the needle will descend toward the center position.
Before it gets there, you will be rudely awakened (if you have a tendency to doze) by the signal that you're passing the Outer Marker, which is confirmed by the light under the O on your panel.
As the glideslope needle reaches the center, reduce your power setting for a 500 FPM descent. (You'll see now how valuable that descent—which you learned so long ago—is on an ILS approach.)
Now keep both the CDI and the glideslope needles centered, using just small increments of aileron for the former and throttle only for the latter. In this approach, you must be precise. If the CDI strays one degree, correct it—keep it centered. If the glideslope needle drifts above center, add a notch of power, or if below, subtract a notch of power to keep it centered.
Do your regular instrument scan, too, but don't be overly concerned with anything other than the OBI and its glideslope. Your VSI will reflect your power changes. You're not trying to hold 500 FPM here; that was just a starting point. What you are trying to hold is two needles, centered, precisely.
You'll see that your airspeed stays just about on your regular slowflight setting—another indication of the precision built into your flying technique.
Do not change trim. Power is your most precise tool here and will serve you well if you use it in the right amount and at the right time.
As you get closer to touchdown, stronger corrections will be required to keep the needles centered. Thus, overcontrol becomes the biggest problem. Try to anticipate the needles and stay ahead of them. If they “lean” in one direction or the other, correct immediately—aileron or power as needed.
I hope you'll be pleasantly surprised when you break out of the overcast—or at least, I hope neither of us will be unpleasantly surprised.
Go ahead and land on 16 at Snohomish. Since you've made a power-on approach, holding the aircraft in an approximate 3-degree descent angle to match the ILS, make an airline-type approach and landing—long and flat—rather than trying to transition to your usual steeper final.
This mode is worth working on often. Here are some variations, done in the Editor, that will make it different and/or more challenging each time:
- Change the heading parameter. Make it any number between 0 and 359 that comes into your head. Change it every time you fly the mode.
- Change your altitude by several hundred feet, up or down.
- Change your North and/or East parameters, adding or subtracting 10 or 15 to or from the original numbers.
- Do any combination or all of the above, starting anywhere.
If your new altitude or position puts you too close to Snohomish, or on the other side of the airport, or too low or high, fly away from or back to and beyond the airport, or gain or lose some altitude to get into a better position.
And finally, to put a real edge on the challenge, lower the ceiling a hundred or so feet. (Before you do that, however, you'll have to excuse me. I have an appointment.)