FLYING THE APPROACH
BY TIMOTHY J. BRILL, ATP/CFII
As an Alaskan pilot and flight instructor, I've had the fun of teaching many people how to fly (specifically tailwheel) airplanes. The simple answer to this sometimes frustrating endeavor is to use your rudder!
Teaching someone how to properly fly a tailwheel airplane is also a good
time to reacquaint or introduce that pilot to stall-spin awareness.
Why? Because you need to use
the rudder to keep the airplane going straight down the runway and you also need
the rudder to tame stalls and prevent spins.
So why not combine the two as part of the tailwheel endorsement?
Dutch rolls are a great exercise to develop aileron-rudder coordination.
You begin the dutch roll by pointing the nose of the airplane on some
distant object. Next you begin to
rock the wings back and forth with the aileron.
What you will quickly discover is that you must add rudder pressure in
the same direction as the aileron input pressure.
Without coordinating aileron with rudder, the nose will wander all over
the sky. This is adverse yaw at
work. Your rudder input is always
two parts: applied in the direction of the aileron (left aileron - left
rudder), then neutral. If done
correctly, the nose will remain on your distant object.
Do them first in level flight, then climbing and perhaps even in a banked
turn. Let's continue.
The first step of the landing process is to "get to the runway."
Sounds simple, but deserving of some additional scrutiny.
A few definitions. The
aiming point is some point on the runway (or anything that may resemble a runway
if you're in Alaska) that you fly your descent to landing pattern/profile in
relation to. The landing point or
touchdown point is the actual point on the runway where the airplane touches
down. The landing point is past the
aiming point. The go-around point
may be based on an altitude and/ or visibility, like an instrument missed
approach, or on a performance consideration, or an obstruction, or anytime the
pilot is not happy with the approach. Keep
your hand on the throttle during the approach in case you need to go around.
With the definitions stated, let's look at some problems.
First, consider the ability of your airplane to get to the runway in case
of a power failure. Most people fly
patterns that are too big. Keep the
pattern tight. Next, consider your
altitude. Most approaches are flown
too low. Stay on, or just above,
your aircraft's glidepath. If you
are on your aircraft's glidepath
you will find that you will be steadily reducing your power as you get closer to
your aiming point. If you have to
add power, you are below your aircraft's glidepath and if you are below your
aircraft's glidepath and you have an engine failure, you will not make it to
the runway. Remember the glide
ratio in most small aircraft is about 4 to 5 degrees.
A vasi or papi is typically 3 degrees.
If you follow the vasi, you will be below your aircraft's glidepath.
Of course, on an instrument approach, you may not have a choice.
Finally, the pitch vs. power relationship.
They are two sides of the same coin.
You cannot change one without affecting the other.
Interestingly most private pilots are taught to use pitch for airspeed
and power for altitude. Instrument
pilots are taught to use pitch for airspeed and power for altitude, but then are
taught to maintain the glideslope (altitude) with pitch and airspeed with power.
Confusing, perhaps, just don't think about it; it works because they
are essentially the same. On final
approach, I try to get the student to maintain a constant airspeed, then use
power "as needed" to get to the aiming point - more power if "low",
less power if "high." Students
can greatly improve their aircraft control with an effective use of trim to
maintain airspeed. I normally
establish my airspeed in downwind, then trim off the control pressures.
You will have to re-trim every time you use flaps or change your
airspeed. This technique works
especially well in windy conditions. The
student quickly discovers in a stiff headwind they need constant "slight"
forward "pressure" and lost of extra power to get to the runway.
Remember, it's forward pressure to establish best glide speed after an
engine failure, for a "dead stick" landing.
Sitting in the back seat of my Citabria during instruction, I cannot see
the airspeed indicator. I
rely on the "site pictrue." Remember,
the "site pictrue" is always correct, the pilot-static airspeed indicator
will usually lag behind.
Once we have made it to the runway, we now have to get control of the
airplane over the runway. In most
bad landings the pilot never really has adequate control of the airplane over
the runway. It can be called a
random arrival, or perhaps just a controlled crash.
So, what is control? Using
"slow flight" over the runway is a good "control" exercise.
Fly final, flair at the aiming point, and just before the aircraft
touches down, add some power. You
can fly the entire length of the runway, under control and most likely in the
correct landing attitude. I
generally add power after I flair when the airplane's energy is reduced.
If you add power too early, you just keep flying.
Once you can get to the runway, flair and fly down the runway under
control in slow flight (try to make some shallow banked turns down the runway,
perhaps even some S-turns. This is
a great exercise to learn the required pressures for cross wind landing).
When the airplanes runs out of energy, it lands.
It's that simple!
As the pilot in command, you essentially manage your aircraft's energy.
There is the energy of motion (kinetic energy) and the energy hidden in
altitude and/or power (potential energy). You
are continuously trading one for the other: Altitude for airspeed; airspeed for
altitude. Of course without an engine, gravity will ultimately win the
energy game and your airplane will land (softly, I hope).
The key for a good landing is to fly a constant airspeed approach, get
control of the airplane over the runway, maintain that landing attitude or site
pictrue, and let the airplane continue to fly down the runway until it runs out
of energy.
Let's now visit the rudder. Most
people transitioning to tailwheel airplanes use the rudder improperly.
The rudder is what will keep the airplane going straight down the runway.
The rudder input is always 2 parts: applied as required then quickly back
to neutral. Quick rudder inputs are
to be used. Remember that Dutch
rolls (as described earlier) and rudder stalls are good rudder exercises.
The rudder stall in particular demands quick feet.
The rudder stall is a stall. Begin
with lot's of altitude. The
instructor controls the elevator and throttle.
Instruct the student to keep the ailerons neutral.
The instructor will stall the airplane and maintain that stall by holding
adequate back elevator pressure. Begin
the exercise with idle power. The
student is now asked to keep the wings level with the rudder.
Again, the rudder inputs are always 2 parts: applied as required to
"lift" the down wing then quickly back to neutral. The airplane may roll violently, and if yaw couples with
roll, may spin. If the student is
aggressive with the rudder inputs, he will prevent the spin by minimizing the
yaw. Adding power above idle will
greatly increase the roll instability. The
student learns how to use the rudder properly.
As I coach students doing these exercises, I've seen a common faults.
First they do not use the rudder. Then
when they realize the importance of the rudder they make big, slow rudder
inputs, without getting back to the neutral position quickly.
As a result, the airplane initially does not respond, then quickly
over-responds past the pilot's expectations.
In a word, over control the airplane.
It's like a wave whose magnitude gets bigger and finally beyond most
pilot's ability to control. The
rudder inputs need to be small and quick. If
the airplane's nose moves left, several quick taps on the right rudder will
correct the problem. Don't stop
moving your feet. Keep dancing on
those rudder pedals.
Airplane control has been spoken of in reference to slow flight over the
runway and the rudder. The key is
not to over control the airplane. Think
control pressure, not necessarily deflections.
Make small corrections often and early, not one large correction too
late.
The landing pictrue is one of several sit pictrues you should
memorize for your airplane. Look
out the front as well as the wings. When
your airplane is tied down on the tarmac, all three wheels are on contact with
the runway. This is your 3-point
landing pictrue. When you establish
control of the airplane over the runway, there is no need to pitch the nose any
higher than the 3-point landing pictrue or you will land tailwheel first.
As the airplane's energy decreases (as airspeed decreases) you may have
to add more and more back pressure, not to change the pitch but to maintain the
3-point landing pictrue you established during the flare.
Think small pressures. When
the main landing gear touches down, power to idle (except soft fields) and stick
full aft. Again, slowly! If you get excited and yank the stick aft, the airplane may
balloon. If so, you have three
choices: A go around, get control of the airplane over the runway and try again,
or cut power, stick full aft, and come right down to a hard 3-point landing.
Most people over estimate how high they balloon.
It is usually not as high as it seems on the ground.
Keep dancing the rudder pedals until the airplane is completely stopped.
If you bounce, that is you hit the ground at high speed, you have the
same 3 a forementioned solutions.
Once in the landing pictrue attitude, the hardest thing to do is BE
PATIENT. Don't rush into a bad
landing. You are paying for air,
not taxi time. So wring out every
inch of flying you can get. Try to
challenge yourself to fly down the runway a little further each time.
Your landings will be great.
Finally, the airplane will land when it runs out of ENERGY. Remember as PIC, you are the airplane's energy manager.
A final word on wheel landings. Lots of new tailwheel pilots think wheel
landings are the rage. The problem with a wheel landing is you have only two points
of contact on the ground, not 3, thus necessitating very precise rate of sink as
well as rudder control. In a wheel
landing you get control of the airplane over the runway with extra energy.
Remember our windy conditions. Now,
when the main landing gear touches the ground, if we were to yank, or even nudge
the stick aft, we are asking our still flying airplane to climb, and it will!
So you can't move the stick aft to perform a wheel landing and you
certainly can't just let the airplane control itself. Your only option is the nudge the stick forward as the mains
roll onto the runway. Keep adding
forward pressure to maintain the 2-point attitude during roll-out until the
stick is full forward. At that point, with aircraft power idle and energy
depleted, move the stick full aft and into a 3-point landing attitude.
Basically, if the airplane wants to land, go 3-point.
If it wants to float, go wheel landing.
(My thanks to Rich Stowell for his input.)
