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.)

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