Instrument Rated Pilot Ground School
Instrument Rating Overview
—by Rod Machado
Okay, time to grab a soda, and get prepared to sip and learn. That's right,
get comfortable, because this lesson will consist mainly of a friendly little
discussion about the principles of instrument flying. No, nothing super-secret
is going to happen. No special handshakes. No passwords. Specifically, we'll
talk about what an instrument approach is and why, when, where, and how it's
done. When you're finished, you should be familiar enough to handle a basic
instrument approach—the kind the pros fly in their jumbo jet airliners. (These
lessons are all available in the ACTIVE FLIGHT SIMULATOR PROGRAM however the
following information is provided so that you can learn from it at your
VFR vs. IFR Flying
In our earlier classes, we spent a great deal of time learning how to fly the
airplane visually by looking at the horizon through the window. Pilots refer to
this as flying VFR, which stands for flying under Visual Flight Rules. But what
happens when you can't see the horizon, such as when clouds are present? Can you
still fly? Yes, you can fly IFR, otherwise known as flying under Instrument
IFR flight allows you to fly in the clouds using your airplane's instruments
to maintain control of the airplane and using your navigation equipment (such as
VOR) to take you to another airport. This can all be done in the clouds without
having to see outside, at least until you're ready to land the airplane, that
is. Landing the airplane always requires that you see the runway well enough to
land (Yes, even if you carry a lot of insurance and wear a helmet with a roll
bar, you still need to see outside to land).
To fly instruments, pilots need an instrument rating, which is obtained after
acquiring the private pilot certificate. It requires additional training in such
things as maneuvering the airplane by its gauges, advanced navigation, and so
on. (And you must also promise not to tell other pilots how much fun it is, or
everyone will want to do it). The bulk of instrument training deals with
learning to scan the instruments, just like you practiced in the three scan
lessons already covered.
You're now ready to move beyond the instrument scan. You're ready for the
next level, which, with some software programs, requires that you slay an
enormous fire-breathing, multieyed beast. Well, not today. Reholster your laser-phaser
and sip that soda, Yoda, because we're going to learn how to fly a full-blown
Instrument Flying: The Big Picture
Instrument flying works this way. First, a pilot files an IFR flight plan
with air traffic control (ATC). This is like making a dinner reservation at a
fancy restaurant in that it alerts the restaurant staff to reserve space for
you. Same with ATC. After the plan is filed and you're ready to go, you
typically call the air traffic control tower at your departure point and tell
them you have a flight plan on file. They say, "Okay, we've accepted your
flight plan and you're cleared for takeoff." It's pretty simple, and,
unlike a restaurant, you aren't expected to leave a tip.
With flight plan and clearance in hand, you depart, climb into the clouds (if
clouds are present), and head on your way. Your objective is to follow the
airways aloft to your destination. These airways are constructed from VOR
courses that crisscross the country. How do you know which routes to follow? The
same way you know which highway to take when you travel on vacation—the
roadmap. Pilots, however, use an aerial version of this roadmap that shows all
these VOR routes along with their minimum altitudes. These altitudes keep you
from getting so low that you knock birds out of trees and people off buildings.
All the while, ATC and its big fancy radar is keeping track of you and anyone
else who happens to be flying IFR in your vicinity. If airplanes get too close,
the radar controller separates the airplanes with verbal commands. No, not
commands like, "Hey, look out!" or "Dive! Dive! Dive!" or
"Oh, the humanity!" The controller simply vectors airplanes (gives
headings to fly) away from each other until the collision danger has passed.
As pilots approach the destination, they reach into their flight bag and
bring out a special piece of paper that seems thin enough to be a Kleenex (but
don't blow your nose with it, or the passengers will think Zamfir, master of the
pan flute, is flying the airplane). The paper I'm referring to is called an
instrument approach chart. It contains detailed instructions on how to leave the
en route portion of the flight, approach the airport, and land, all the while
using some means of electronic navigation (typically VOR). Most big airports
have one or more of these instrument approaches (and charts). Figure 1 shows a
typical VOR instrument approach chart.
The Approach Chart
Instrument approach charts have several things in common. First, at the top,
they show the frequencies you'll use to talk to the local air traffic
controllers (section A). Below this is a plan view, which shows the electronic
navigational aids that you'll use to fly to the airport (section B). Below that
is something known as the profile view, which gives you a few of the preliminary
minimum altitudes you'll use as you descend to the airport (section C). Finally,
at the bottom, is the minima section (section D). This shows you the minimum
altitude to which you can descend as you fly toward the airport.
There is a point known as the missed approach point, or MAP, and it's shown
on all approach charts. At the MAP, the pilot must see the runway clearly enough
to land. This point is normally shown by the symbol "M" in the profile
section (section C). If you can't see the runway clearly enough from the MAP,
you must make a missed approach. This means you'll most likely go to another
airport that has better weather.
Now that I've marinated your noodle with these ideas, I'm sure you're curious
about how to fly an instrument approach. Let's find out. While there are several
common types of instrument approaches, let's examine the most common one first.
It's called the VOR approach.
The ILS Approach
The ILS consists of two electronic beams: one provides horizontal guidance;
the other, vertical guidance. What makes this approach more useful than a VOR
approach is that it takes you directly to the runway and sets you up for a
landing from a comfortably low altitude. The VOR (and other approaches) just
take you over the airport, sometimes at hundreds of feet above the runway. This,
of course, makes it more difficult to transition from the instrument approach to
the actual landing. The localizer portion of the ILS is much more sensitive than
the VOR course. By sensitive, I don't mean it 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
(Note that the glideslope needle is also quite sensitive).
Figure 2 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 (NAV 1, the top receiver
in the stack of two), sets the VOR display to track one and only one specific
course that's precisely aligned with the runway. This is called the localizer
course, and, in the case of Portland, it's aligned in a direction of 279 degrees
Once the localizer frequency is tuned in, you can set the OBS to the inbound
course for a heading reference (although the OBS is nonfunctional, since the VOR
receiver is now tuned specifically for the localizer course only). Tuning in the
localizer automatically activates a specific glideslope frequency, which is not
shown on the approach chart.
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 the 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 (assuming you don't go below
the glideslope and start knocking birds out of trees and people 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 your local 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 decision height, or DH,
which is 280 feet, as shown at position G in the minima section. DH is your
missed approach point, and if you don't have the runway in sight by this point,
you must execute a missed approach. Yes, I know there is an "M" shown
at the beginning of the runway (position H). 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 won't work). Therefore, the
dashed line (position I) in the profile view shows the MDA for the localizer
approach, just like the step-down altitudes you saw on the VOR approach. If I
were cleared for a localizer approach, I'd cross the outer marker at 1,900 feet
(position J), descend to 560 feet (position K), and fly to the MAP. The MAP is
identified by time (based on a specific groundspeed from the outer marker) or by
DME on the localizer, as shown by position L.
Most everything else about this approach chart should now be familiar to you.
For example, suppose you're over Battle Ground VOR (position M) and ATC clears
you for the approach. The feeder route from BTG to the ILS is the 135-degree
radial (position N). Set your VOR to track outbound on this radial until the
localizer is intercepted. How will you know that you've intercepted the
localizer? You can set one navigation radio (the bottom one) to navigate from
BTG VOR and the other navigation radio (the top one) to receive the localizer.
As you track from BTG VOR, you'll know you're over the localizer when the
localizer needle centers. The outer marker beacon display will also activate in
the cockpit as an additional clue, since the 135-degree course takes you to
LAKER intersection (located on the localizer).
At LAKER, fly 099 degrees (position O), descend to 3,500 feet (position P),
and make a procedure turn within 10 nm of LAKER. There is one important item you
must know about localizers. Because the localizer is a single electronic beam,
tracking opposite its inbound direction results in the needle appearing to read
in reverse. In other words, when you are flying outbound from the localizer, if
the localizer needle moves in one direction (right or left), you must fly in the
opposite direction (left or right, respectively) to center it. This is known as
reverse sensing. Therefore, as you prepare to fly the procedure turn by tracking
outbound on the localizer, you'll have to fly opposite the direction the needle
swings to keep it centered.
Once you've completed the procedure turn and are inbound headed 279 degrees,
the needle will indicate normally. You may descend to 3,000 feet (the glideslope
intercept altitude) once established inbound on the localizer and after making
the procedure turn. Track the localizer, and fly the glideslope down to DA.
We'll talk more about how to fly an ILS shortly.
That's a lot for an overview, but at least you've been exposed to the
fundamentals of flying instrument approaches. Perhaps you feel like you've been
exposed to a concussion, too. Granted, it does take a little practice to get
good at this. However, flying instrument approaches is a lot of fun. It's even
addictive. So don't be surprised someday to find yourself undergoing instrument
flying withdrawals if your computer breaks down.
Earning a Flight Simulator Instrument Rating will make you a more versatile
and proficient pilot. You'll enjoy new experiences with Flight Simulator's
navigation and weather features. You'll do your instrument training in the
same aircraft you used for your private pilot certification, the Cessna 172.
While the basic maneuvers are the same, this time you'll learn to perform them
solely by reference to the instruments. You'll master the art of the instrument
scan and learn the intricacies of flying instrument approaches. (These
lessons are all available in the ACTIVE FLIGHT SIMULATOR PROGRAM however the
following information is provided so that you can learn from it at your
There are few thrills in aviation like taking off into the clouds, flying
for a few hours, and then breaking out with a runway at another airport in
sight directly ahead. By the time you finish your instrument training, you'll
be capable of getting from here to there in almost any weather. Here are the
Lesson 1: The
Learn how to use the VOR to get you down to the runway at Paine Field. This
non-precision approach requires precise flying and timing to find the runway
through the clouds.
Lesson 2: The
In this lesson on a precision approach, the Instrument Landing System (ILS)
helps you fly to lower altitudes without visual contact with the ground, which
translates into a better chance of landing in bad weather. The skills you
learn in this lesson transfer directly to your instrument training in the
Airline Transport Pilot lessons.
Lesson 3: Holding
Learn how to "park the airplane in the sky" in a holding pattern
over the Paine VOR. It's not unusual for air traffic control to ask you to
delay your flight by holding at a specific place and asking you to fly a
"race track" around a radio navigation aid, in this case a VOR.
Instrument rating solo flights
The first solo flight is perhaps the most important. First read about the
techniques of instrument scanning, and then practice them in a flight. Without
the instrument scan, controlling the airplane in the clouds will be virtually
impossible. The navigation is not difficult, but controlling the airplane
solely on instruments does take practice. The remaining solo flights help you
perfect your instrument flying skills. THIS LESSON IS
AVAILABLE IN THE ACTIVE FLIGHT SIMULATOR PROGRAM
Instrument Rating Checkride
Here's where you show the examiner how you control the airplane in the
clouds. It'll be a cloudy day for your flight in the Cessna 172. Once you
pass, you'll be awarded the Flight Simulator Instrument Rating certificate. THIS
LESSON IS AVAILABLE IN THE ACTIVE FLIGHT SIMULATOR PROGRAM