Runway USA

A pilot's guide to destination cities in Flight Simulator
by Charles Gulick

On the Glide Path


Well, this day started out beautifully, but the east wind brought in some heavy weather in the last hour. Consider yourself lucky, because this will give you a chance to make an ILS (Instrument Landing System) approach to San Jose. The existence of an ILS on the airport is another reason I chose San Jose as the optimum home airport in the area.

You'll need the ILS this morning. Contact Oakland ATIS on 128.5 and see what the ceiling is. (Nimitz has no tower, and Oakland is only about six miles southeast of us. San Jose, as of this writing, has a tower, but the frequency listed on the chart and in the manual is incorrect. After a search of the frequencies, I have a feeling the tower is not currently operating.)

Ceiling 200 feet, it says here. Now that will call for all your expertise!

First, let's assess the situation and plan what we're going to do.

Since the cloud tops are at 6000 feet, it doesn't make sense to fly over the weather. San Jose is only about 31 NM from here. We'd have to start letdown before we even got on top, plus we'd be in poor configuration to lock onto the ILS.

Further, we have no mountains to be concerned with, since our course will essentially be over the bay and a little bit of the eastern shore.

So we'll fly in, rather than over, the weather.

The optimum altitude for interception of the ILS is 1800 feet. So we'll fly at 1800 feet all the way to intercept.

The ILS at San Jose operates on Runway 12R, and the heading is 123 degrees. So we'll use NAV2 to track the San Jose 123 radial and keep NAV1 tuned to the ILS frequency all the way. (The ILS is bundled with NAV1 only.) It doesn't matter what radial we set on the NAV1 OBS; since we're not tuned to any OMNI station, but rather to the San Jose ILS, NAV1 is now an ILS instrument only.

We're set for departure on Runway 13 here at Nimitz Field, which means, of course, that the runway bears approximately 130 degrees. Our takeoff heading puts us in the desired general direction, but we want to be absolutely precise. This is no time for hunches of any kind.

Set NAV1 to the San Jose ILS frequency, 111.1. It'll continue to read OFF until we're in range of the ILS, and you'll get no DME indication.

Set NAV2 to the San Jose VOR frequency, 114.1. Then center its needle to see what radial we're currently on—it's the 128th.

Now set the NAV2 OBS to 122 degrees—again, as close as we can get to 123 degrees, but as you do, note carefully how the OBI needle moves. It moves a full mark for each two degrees of change. This means that the odd radials, like 123, lie between any two of the needle markings. So to fly precisely on the 123 radial, we'll want to keep the OBI needle exactly a half-mark to the right of center when set to 122 degrees. Experiment with the settings a bit until this is absolutely clear to you. A degree does make a difference when you're flying an ILS approach—particularly with a ceiling such as we have today.

So our initial flight plan is this:

With NAV1 dedicated to the San Jose ILS on a frequency of 111. 1, and NAV2 set to the San Jose VOR on a frequency of 114.1, we'll take off and climb to 500 feet. That puts us above pattern altitude. (Some other pilot may be flying in these same weather conditions.) Planning on a cruise altitude of 1800 feet, optimum for the ILS interception, we'll fly the OBI2 needle to get and keep it—not centered, but a half-mark right of center. That's where we'll keep it until the ILS comes into play; then the ILS indications on NAV1 will be our directional reference. Remember, for maximum efficiency, take a healthy cut toward the radial you want when you turn (about 60 degrees). You'll see OBI2 respond smartly.

Go ahead and take off now, executing the initial plan just described. Then come back to this text when you're straight and level, on the 123 radial for San Jose, at 1800 feet.


Okay? So now transition to slowflight, holding your altitude and keeping the OBI needle where you want it. When you've slowed down, put on 10 degrees of flaps. (That's all the flaps we'll use, from here all the way to touchdown.)

Once you're straight and level in slowflight, use power—and power only—to make any desired changes in altitude, until you've completed the ILS approach and have the runway in sight.

When NAV1 and its ILS needles become active (there'll be an initial deflection, which you should ignore, when the DME turns on about 17 miles out), give them a chance to settle down and then regard them as your sole directional reference, for both right/left and up/down. The vertical needle will come into play first, and the FROM reading will switch to TO. From that point on, keep it centered; it's reading your relationship to the glide path, not your heading. When the horizontal needle comes into play, don't chase it until it moves to the center position, at which point put on carburetor heat and reduce power to start a 500-FPM descent. Then fly both needles as you would normally fly the OBI needle, turning toward and climbing or descending toward them, respectively. Correct constantly to keep both needles centered, using small amounts of aileron for directional control, and small power changes for vertical control. Ignore any other heading references.

Follow every movement of the needles with immediate corresponding control changes. There's no time available for daydreaming when you're flying an ILS approach.

Toward the very end, your ILS needles may cavort wildly, but within seconds you'll break out of the overcast. When that happens, of course, take over visually and complete your landing.

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