Airline Transport Pilot Ground School
Transport Pilot Lesson 3: Full ILS
Approach - BRIEFING
In this lesson, you'll learn to fly a full ILS approach in the Boeing 737.
ESTIMATED TIME TO COMPLETE
You should complete all Student, Private, Commercial, and Instrument
lessons before beginning this lesson. Reading the Ground School material
before starting this lesson will help you better understand the skills being
taught and terminology used in the lesson.
You'll encounter mostly cloudy conditions with some rain. Low ceilings are
forecasted, so you will need to fly the aircraft referring only to the
ABOUT THE FLIGHT
In this lesson you will fly a descent and full ILS approach into Boeing
Field. You can either hand-fly the lesson or use the autopilot for the entire
lesson. This lesson does not teach using the autopilot, so you must bring
those skills to the lesson if you choose to use the autopilot.
- You'll need to be familiar with how to adjust the CDI in this aircraft.
- You'll need to know how to tune the radios, including changing
frequencies between the active and standby positions.
- You may want to have a pad of paper and pencil handy for quick
calculations and to copy your clearance. You may also want to print the
- This lesson assumes you know how to use the autopilot (if you elect to
use it) or are proficient with precise pitch, speed, and altitude control
of the aircraft.
KEY COMMANDS TO REMEMBER
F7 to operate the flaps
G to operate the landing gear
Shift + / (slash) to arm spoilers
You'll be asked to maintain:
- Airspeed within 15 knots as assigned
- Altitude within 200 feet as assigned
- Headings within 10 degrees as assigned
- Bank no more than 10 steeper and no more than 5 degrees shallower than
- Power settings within no more than 2% above and no less than 5% below N1
- Pitch attitude within 3 degrees as assigned except on landing flare,
where pitch angle should be no more than 5 degrees and no less than 2
degrees nose-up pitch attitude
- Vertical speed within 400 feet per minute during descent
The full ILS approach - LESSON
by Rod Machado
Years ago a flight instructor was asked what the letters "ATP"
meant. He replied, "Always Totally Proficient." Well, it doesn't
quite mean that, but the definition is close enough for our purposes. After
this lesson you will be "almost" totally proficient in flying ILS
approaches in the Boeing 737.
This lesson will cover the details of making an ILS approach in the Boeing
737. In it, you'll have a chance to apply all that you've learned on the two
previous ATP lessons. So let's begin at the beginning of the approach.
Now that we know the local airport conditions, the local altimeter setting,
and the expected active runway for arrival, we can begin to get organized for
the approach. This is especially relevant since a major organ--your brain--is
involved in this process. Now is the time to review the approach chart for the
approach you'll fly. If you haven't done so already, this is an excellent time
to use the autopilot to fly the plane while you focus your attention on the
approach information. (You can read my brief article, Autopilot
Fundamentals, or you can learn a lot more about it in the Learning
Center article, Using the Autopilot.)
- The pre-approach briefing should take place prior to reaching the
initial approach fix. Make sure you have the correct chart for the
airport, runway and approach used.
The key elements to briefing include the following:
- The airport elevation.
- The primary navigation aid and its frequency.
- The direction of the inbound course.
- The altitude at which the glide slope is intercepted.
- The name of the final approach fix.
- The minimum descent point (such as altitude, DME, or time, depending on
the type of approach).
- The missed approach procedure.
- Any specific visibility requirements (such as 1 mile or 5,000 feet).
You most likely will not be tuning the radios and setting inbound courses
at this point. This will be done when it is time for the Approach checklist.
We still need to follow a standard arrival procedure or follow ATC's
instructions as they vector us down from cruise altitude.
We've already covered the basics of descent planning and speed control and
now it's time to transition into the airport environment and land. As a Flight
Simulator pilot equipped with the appropriate approach plates for the airport
and runway, there is often a coverage gap in the charts between the end of an
arrival and the entry to the charted approach procedure for the runway of
choice. If you are flying using the ATC features in Flight Simulator, you will
be radar "vectored" (given specific headings to fly) onto the final
approach course. If you are flying without ATC, you will need to plan to be at
a certain altitude, speed, and heading in order to successfully intercept the
final approach course properly configured.
Approach and Landing Tips
- Be 3,000 feet AGL when 10 nautical miles from the runway: Gear
down—Flaps 15 and 160 knots
- Be 1,500 feet AGL when 5 nautical miles from the runway: Gear
down—Flaps 30 and 150 knots
You can adjust your seat "viewpoint"
during takeoff-climbout and cruise if you prefer to see the ground during these
phases of flight.
Merely hold your SHIFT key down, while pressing your ENTER key once. Tis will
raise the pilot's seat. To get back to the seat's original
position, just press the SPACEBAR once! (Try experimenting with this
while your aircraft is parked. Pretty soon, you'll get the "knack."
A rough rule of thumb for this approach transition area is to plan to be
3,000 feet AGL at 10 nautical miles (nm) from the airport, while properly
configured and established on the localizer. Approaching this 10 nm point you
want to be slowed to no more than 170 knots with flaps set to 5. (Shown in
Figure 3-1) As the glide slope "comes alive" (starts moving away from
a full deflection) you will want to extend the gear, increase flaps to 15, and
slow to 160 knots. At 3,000 AGL and 10 nm out, you should be close to
intercepting, if not on, the glide slope. (Shown in Figure 3-2) Keep in mind
that these are approximate altitudes and distances to place you close to a 3
degree descent path for final approach. Each approach is different to allow for
items such as terrain or ground obstructions. At the final approach fix (FAF)
set flaps 30 for landing, set power between 53 percent and 55 percent N1, and
fly the glide slope down to a smooth landing.
Whether you are being vectored by ATC or have followed your own descent path,
the key to a successful approach and landing is being prepared. This means you
have the right chart out for the approach (as you have already done during your
descent checklist right?) and have tuned the radios to the correct frequencies
and set the inbound course. Briefing yourself on the approach procedure and key
altitudes is important, as is having the proper mental image of the procedure so
that you can stay ahead of the approach.
The Approach and Landing
Once you're established on the localizer with the glide slope indicator
"alive," configured with the gear down, flaps set to 15, and slowing
to your target speed of 150 knots (or the appropriate Vref speed for your
weight, if you are going to that level of detail), you are ready to intercept
the glide slope and fly it on down to the runway. At the point of glide slope
intercept from below where you're still "one dot low" (as shown in
Figure 3-3) with the glide slope needle moving downward, set the final landing
flaps to 30 and set your power to about 53 percent N1. Begin your pitch down to
0 degrees and monitor your position left or right relative to the localizer and
high or low relative to the glide slope.
Tracking an ILS
The best way to fly an ILS approach with the needles centered is to be
properly configured, trimmed, and on speed at the final approach fix. To correct
flight path deviations, make frequent, small corrections when tracking the
localizer and glide slope. Waiting too long to fix a deviation will send you
into "pilot induced oscillation" getting you farther behind the
process. It could also result in knocking down a few trees by not remaining on
Tracking the Glide Slope
If you are above the glide slope with the pitch set correctly at 0 degrees,
then reduce your pitch to recapture the glide slope while simultaneously
reducing power by 1 percent to 2 percent N1 to keep your airspeed from
increasing. If you are below the glide slope with the pitch set correctly at 0
degrees, then increase your pitch slightly to recapture the glide slope while
simultaneously adding power (1 to 2 percent N1) to keep your airspeed from
decreasing. The secret to recapturing a wayward glide slope needle is to make
pitch and power changes simultaneously. This helps you maintain the desired
airspeed during the recapture. If you're on glide slope and your airspeed is
either too high or too low, then make a 1 to 2 percent N1 power adjustment while
moving your elevator to maintain the desired pitch. If your pitch is not
stabilized, you will have a difficult time capturing and staying on the glide
slope. If you maintain the configuration, pitch, and power settings provided,
use small power adjustments to maintain the glide slope.
Tracking the Localizer
If you are left of the localizer course but on heading: turn right 2 degrees,
level the wings and be patient. As you recapture the localizer, turn back to
your inbound course. Use the opposite technique if you are to the right of
course. If you are 2 dots or more off centerline, turn to a heading up to 5
degrees off the inbound course, and level the wings. Use the width of the
heading bug to limit the degrees of correction to use. It's wise to avoid
banking more than half of a standard rate turn when making course corrections on
an ILS. Again, make small changes and have patience.
You can also get a lot of help learning to fly an ILS from the Flight
Director mode on the autopilot. I'll let you read about that on your own.
The Instrument Scan
Making small, frequent corrections means you will need to scan your
instruments rapidly, as you learned in the instrument rating lessons. The
technique for scanning instruments in the Boeing 737 is a little different than
the Cessna Skyhawk, but your earlier training should help a lot here.
The primary instrument to use as the center point is the artificial horizon,
or the attitude direction indicator (ADI) in this aircraft. The goal is to start
at the ADI, reference the other key instruments one at a time, returning to the
ADI. HSI refers to the Horizontal Situation Indicator; VSI refers to the
Vertical Speed Indicator.
Instruments to scan: 1–ADI; 2–VSI; 3–HSI;
4–Airspeed indicator; 5–N1 percent; 6–Altimeter
One scan pattern that works well for the Boeing 737 is the following:
ADI, VSI, ADI (1, 2, 1)
ADI, HSI, ADI (1, 3, 1)
ADI, VSI, ADI (1, 2, 1)
ADI, Airspeed Indicator, ADI ( 1, 4, 1)
ADI, VSI, ADI (1, 2, 1)
ADI, N1 percent, ADI (1, 5, 1)
ADI, VSI, ADI (1, 2, 1)
ADI, Altimeter, ADI (1, 6, 1)
Try not to fixate on any one instrument. Take a mental snap shot of the
instrument as you return your scan to the ADI. Apply required corrections as you
scan other instruments: this is the fun part. Skip instruments you do not need
to scan. If your airspeed is where you want it and stabilized, you can skip the
N1 percent check in that round.
As you near the approach end of the runway, the localizer and glide slope
needles will be more sensitive (so don't make fun of them). These needles will
show a change faster than when you began the approach. Resist the temptation to
apply big corrections down near the bottom of the ILS. Use the same small, but
frequent corrections and you will keep ahead of the process.
So, a properly configured and well trimmed airplane is easy to fly. Remember
- Set N1 percent power in the specified range
- Use the target speeds as recommended
- Use the flap settings specified
- Fly the pitch as recommended
By keeping those four points in mind, the needles will move slowly and be
easy to correct.
You might also want to review (and perhaps print) the approach and landing
reference tables: Straight-in
Visual Approach and How to Land.
Does it get any better than this? Maybe, but you have to admit that flying an
ILS approach in the Boeing 737 is a wonderful experience. I think you're ready
to give this ILS lesson a try. So have at it. Just remember that it takes
practice to get good at anything. So feel free to review this ground school
lesson as many times as you desire and print the quick reference tables. Suppose
that during the ILS, the localizer and glide slope needles keep hitting their
stops as they race up, down, right and left. If this happens it's possible that
one of your passengers might say, "Hey, I think you left your turn signal
on." If you hear this, don't be embarrassed. Just keep repeating this
lesson until those needles remain steady during the approach. That's called
Ok, see you in the cockpit. Click the Fly This Lesson link to practice
what you've just learned.
THIS LESSON IS AVAILABLE IN THE ACTIVE FLIGHT