User Guide

Flight Simulator
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will cry if you yell at it. I mean that the needle response to course deviation is quicker than that of a
VOR. This makes it a little more challenging to keep the needle centered in the display. (The
glideslope needle is also quite sensitive, so don’t yell at it, either.)
Figure 14 shows the ILS Runway 28R approach chart for Portland International Airport (position A).
The localizer frequency is 111.3 MHz (position B). Tuning this frequency in your number one
navigation receiver programs the VOR display to track one and only one specific course, which is
precisely aligned with the runway (just in case you forgot, NAV 1 is the top receiver in the stack of
two). This specific course is called the localizer course and, in the case of Portland, it’s aligned in a
direction of 279 degrees (position C).
Once the localizer frequency is selected, you can set the OBS to the inbound course for a heading
reference. (We set this value in the OBS as a memory aid. The OBS is nonfunctional because the
VOR receiver is now tuned specifically for the localizer course only.)
Let’s assume that you’re at 3,000 feet (the glideslope intercept altitude) at position D. You’re flying a
heading of 279 degrees and the glideslope needle located within the VOR display is above the center
position. This means you’re below glideslope. As you maintain 3,000 feet, the glideslope needle will
eventually center (meaning you’ve intercepted it). Now you can begin your constant-rate descent as
we’ve previously discussed.
Instead of making the step-like descents as you did with the VOR approach, the ILS allows you to
follow an electronic beam down to the missed approach point while avoiding all obstructions in your
path. (This is assuming you don’t go below the glideslope and start knocking birds out of trees and
chimneys off buildings.)
As you begin your descent on the glideslope, you’ll fly over the outer marker, shown by the feathered
vertical area in the profile (position E). This activates a blue marker beacon light in the cockpit (and
an alarm that sounds just like the beeper that goes off when the fries are done at the burger joint).
The outer marker notifies you that you’re at a specific point along your descent (5.2 miles from the
runway, as shown in the profile view at position F).
How low can you go on the ILS? All the way down to DA, which is 280 feet as shown at position G in
the minima section. If you don’t have the runway in sight by this point (as well as ½ mile visibility),
you must execute a missed approach. Yes, I know there is an “M” shown at the beginning of the
runway (position H).
ILS without a Glideslope
Sometimes pilots elect to fly this approach without using the glideslope. They do so because they
don’t have a glideslope receiver or the glideslope isn’t working at the airport (someone may have
yelled at it, hurt its feelings, and now it refuses to work). Therefore, the dashed line (position I) in the
profile view shows the MDA for the localizer approach, just like the stepdown altitudes you saw on