Contents:
...Prelanding; ...Beginning
Landings; ...Stabilized approach; ...Airspeed Control; ...The Approach;
...Generic Landing pattern; ...Do,
by trying not to; ...Using anticipation;
...Ground Effect; ...The landing;
...Landing Stall; ...Touchdown;...
Post-Landing Techniques; ...Salvaging
the Landing; ...Landing speed; ...Glide Speeds; ...Touchdown
speed; ...Landing roll;
Prelanding
The prelanding begins well away from the destination airport.
From cruise flight we must plan our descent. This usually means
we must decide at some point to change altitude into airspeed.
It is usually, but not always, done by planned reductions in power
and mixture adjustments as required. There are advantages to getting
the ATIS as far out as you can. Sure, the ATIS may well change
before you arrive but not so much as to affect the advantages
of prior knowledge.
From the ATIS you have planned your arrival to include selection of your initial call-up point, radio procedure planning, situational sensitivity, best pattern entry, and your 'what if' options. At a constant point in your pattern arrival you complete the initial components of the prelanding checklist.
For non-complex general aviation aircraft, my preference is to have a pre-landing count system that uses my fingers for up to ten items. As I identify an item I use an appropriate finger. Others go through the process and then check the list. However it feels best to you, you should always run through your prelanding checklist.
Prelanding in the options pattern abbreviates the checklist into gauges and instruments, traffic and clearance. Options approval from ATC gives you a choice of a touch-and-go, go-around, stop-and-go, and full stop. ATC may preclude any of these at their option for traffic considerations.
Copy ATIS........Think............................GUMP
Fuel/Mixture.......Gauges/instruments.......Go-around procedure
.........................Type of entry................ Position
and traffic
..........................Altitude......................... Frequency
..........................Pattern altitude
Beginning Landings
(Instructor)
On our first inter-airport flight, I select a practice area
somewhere in between to do a series of landing patterns at altitude.
I use the same headings as would be expected at our destination
airport. I usually select a climb to 4200' over some hills that
will keep us within 3000' of terrain. At 4200' we enter the downwind
heading, the pilot performs the pre landing check. At the 'numbers'
he applies carb heat, reduces power to 1500 RPM, moves the trim
wheel down three full turns using only the index finger, applies
sufficient back pressure to maintain 4200'. He allows the aircraft
to decelerate to 60-knots while holding heading and altitude.
This is a vital series of skill applications. It may need to be
repeated several times to acquire a satisfactory level of performance.
It usually helps to have the student say aloud what he is doing.
This information on the tape recorder is very helpful for later
review.
The momentum of the aircraft from the numbers to the point that the preceding configuration is achieved covers just the distance to the 'key' position. This is the point at which the base turn is commenced and descent begins. As with all turns, clearing is performed, pressures and added and released on yoke and rudder to smoothly make 90-degree turns in 30-degree banks at 60 kts. (Remember, we practiced these descending banks and turns earlier in our training.)
The difference in this lesson to prior trim and flap lessons is that we are practicing the landing sequence. All turns will be in left pattern until the go around or in right pattern until the go around. In line with the teaching/learning precept that a first learned procedure will also be the first reaction in an emergency, the go-around is the first taught landing operation. This process is first introduced with an imaginary 'ground level'. At altitude and airspeed of 60 kts the student applies a count of 4 to the flaps. As the flaps go down, forward pressure is applied to the yoke to maintain 60 kts. One full upward turn of the trim should keep the speed at 60 kts without any yoke pressure. After simulating downwind, key position, trim, flaps and airspeed, base and final the go around is performed. The sequence of SMO O O TH power C. H., rudder, flaps up 20 degrees, airspeed of 65, climb attitude, flaps up, and trim should be repeated as on many previous flights. From this 'good beginning' the remainder of the pattern usually follows quite easily.
Stabilized
approach
The stabilized approach has no peer in affecting good landings.
Set as many constants on the landing approach as you can. Set
the power to a predetermined constant. Know the trim movement,
and setting required for every change in power and flap change.
On final establish your flight glide path and sideslip for runway
alignment. Trim for the airspeed after setting a constant power.
After flaps are constant, use power to adjust touchdown zone in
very small reductions.
A good landing begins on a correct downwind being flown. Enter every downwind at the same speed and make speed adjustments on the downwind according to traffic. Use a consistent attitude, airspeed, and power combination. Select flaps according to wind direction and velocity. Once you have leveled off in the flare, use gradual yoke and power changes to maintain a smooth nose-high descent to the touchdown. Keep the nose straight with the rudder and centerline alignment by sideslips. the more consistent you are in your approach configuration settings the better able you will be to make any adjustments or corrections.
Think about keeping the airplane from touching the closer you get to the ground. This will help you keep the nosewheel off the ground and touchdown on the mains. The closer you are to a full stall on touchdown the better the landing and the slower the landing speed. Lift UP on the yoke and hold it all the way up and back until the nose falls by itself.
After a good pattern and stabilized approach comes being trimmed for the speed. Trim, and retrim as required to get and hold the desired speed. If you must apply pressure to hold a speed you MUST make a trim adjustment. If you change power, you must make a related trim adjustment to hold the same hands-off speed.
Adendum
The landing is a problem for every new pilot. You have a minute or so to transition from using all the aircraft's energy to keep flying and allow it to dissipate by conversion into loss of altitude and reduction in airspeed. A landing is just another form of flying.
First you must begin and continue to change the configuration and performance to achieve the most controllable and safe approach to the runway. The approach includes the traffic pattern you fly down to just short of the runway You must plan and perform so as to run out of altitude and flying speed at the same instant.
Parallel alignment with the runway is more important than being on the center line. As you approach the runway you look at the end of the runway and the sapce between it and the nose of your aircraft. You will see the space getting shorter if you are high and longer and flatter if you are low. When the space remains constant you have discovered the one spot where you are going.
Airspeed
Control
Landing an aircraft is an exercise in energy control. The
major factor in this is control of airspeed. Every phase of the
landing process has an airspeed or an airspeed range that provides
the maximum safety and utility in the process. I do not teach
a range of operational speeds for takeoff, landings, or climb.
On downwind, base and final there are a recommended airspeeds.
The final approach speed is 1.3 Vso except during gusty conditions.
Vso is the calibrated power off stall speed of the aircraft in
landing configuration and forward C.G. Vso is calculated on actual
landing weight. The POH Vso is calculated on gross weight. The
critical Vso on final can be too fast, too slow, adjusted for
weight, gusts, and airspeed indicator corrections. I always teach
speeds with a margin of operational safety for the student. This
margin is not usually revealed to the student.
If you fly an approach at 10% faster than 1.3 Vso, not only will your have a flatter and much longer over the fence, your rollout distance will be twenty percent longer after touchdown all other factors being equal. An approach thirty percent greater than Vso will require 100% additional rollout distance. If you are at a weight less than the maximum gross landing weight you can expect to float longer at Vso before touchdown and hopefully stop in less distance after touchdown because of increased braking efficiency. What this means is that if you have a weight 10% below POH landing gross you should decrease your Vso calibrated airspeed by rule of thumb 5%. This is done because all aircraft stall at slower speeds when they are lighter.
The Approach
I have, on more than one occasion, watched a pilot have all
the variables of a landing into the air at the same time. Power
up then down, airspeed down then up, approach path high to low
and back again. Runway alignment moving side to side and the nose
swinging back and forth. As an instructor, I find it difficult
not to provide salvaging information. However, a recent pilot
asked that I give him a pattern without saying anything. The approach
was a revelation to the student as to his procedures as well as
a revelation to me that letting the pilot get into trouble was
certainly one way to get his attention focused on my instruction.
The stabilized approach begins from a high-speed descent and ends at the tiedown. At every intermediate point the pilot is reducing the variables that he is expected to juggle one by one. Normal entry into downwind is when the pilot begins to configure the aircraft for the pattern. the pre-landing checklist, including gear down is completed. At the numbers the power is set for a pre-determined constant. A reduction that will give 1500 rpm or 15 inches are acceptable settings. Further power changes should be made to maintain power constants as necessary. The entire landing to touchdown can be accomplished with no changes to this power setting.
A pilot whose initial training did not include emphasis on
the stabilized approach is more likely to make compound corrections.
Power will be added at the same time the nose is raised when low
on the glide path. The nose may be lowered to bring up the airspeed
and correct being high on the glide path. These procedures often
fail to correct the problem and must be repeated several times.
Above the glidepath and fast requires both a power reduction or
additional drag along with a higher pitch attitude.
Making decisive correction of airspeed, attitude and configuration
means that the student must know what element of glide slope control
is going to be decisive. The early detection of small errors allows
either small adjustments or, as in the case of flaps, a delay
until a full increment can be used to make the correction more
permanent. The stabilized approach is the antithesis of the compound
correction. The only solution for being low on the glide slope
is a full power correction while maintaining approach speed with
yoke pressure for an estimated time period or until the nose touches
the far end of the runway. There are three ways to correct being
high. First, flaps as conditions allow. Second, power reductions
that will allow interception of the glide path. Third, reduce
airspeed to increase rate of sink over distance flown.
The constant airspeed means that the controls will perform in a constant manner. The stabilized approach is the basis upon which a hands-off landing can be made down to the flare. Being able to trim accurately for the airspeed stabilized approach gives you the final useful constant. Knowing how the controls will behave reduces the likelihood of excessive or improper control movement.
The flap settings are made according to wind conditions with trim adjusted for hands-off airspeed. (Flap changes are best never made below 200' AGL because the variables will once again will be in the air and the stabilized approach lost.) With all configurations constant and on final, the airspeed (Pitch attitude) is set and trimmed for the final approach. Airspeed is energy. Too much airspeed causes float and wasted runway.
Too little airspeed will increase the sink rate and perhaps a short or hard landing. The POH airspeed is based on gross and may be lower if the approach is flown below gross. Even slight changes in airspeed make large differences in the way the float and flare react to elevator movements.
By maintaining a constant indicated airspeed the pilot is able to make considered judgment as to the glide path. Knowing the glide path's relationship to the runway is a stabilized approach enables the pilot to determine the expected landing. Once established you have two points in mind. There is an aiming point at which point you will flare and a touchdown point a distance beyond. The pilot still has several variables that allow him to vary the distance between the aim point and the touchdown point.
Runway alignment can be visually determined by reference to the centerline of the runway. If the runway does not make a vertical line on the windshield, then the airplane is not lined up properly.
Flaring high and reducing the power to off quickly can cause the plane to settle abruptly, so abruptly that the one-second human reaction time is just enough delay to allow ground contact. Depending on the remaining kinetic energy the plane may stay on the ground or rebound back into the air. Any attempt by the pilot to salvage the landing is likely to result in severe aircraft damage. The go-around is the best option if the aircraft is not firmly on the ground.
Flaring low can greatly extend the touch down range by keeping the power at 1500. The low flare takes advantage of the drag reducing capabilities of ground effect. This capability is a seldom-used capacity by those pilots who have never taken glider training.
The normal flare occurs with the wheels near hip high above the ground with 1500 RPM. Once the round-out speed has reduced we feel a slight singing-elevator sensation. We begin to increase the back and up movement of the yoke while at the same time in 100-RPM increments we reduce the power. One effective procedure is to fix the nose on the far end of the runway and wait for ground contact. The ideal is that at the moment the yoke is full back and the power all the way off, ground contact occurs. In the less than ideal landing the ground contact is made with the main gear and the nose wheel held clear of ground contact. Any power remaining is removed at moment of ground contact.
Generic Landing
pattern
The landing climaxes at the point of touchdown but will not
end there. Furthermore, the beginning of a particular landing
occurred at some past landing where a lesson was learned when
the pilot was high, low, fast, slow or out of control. The mistake
of the past is avoided, corrected and blended into a successful
landing. Not perfect, just satisfactory.
The satisfactory landing begins with aircraft control. Aircraft control is the pilot's ability to perform the four basics of climb, descent, level, and turns within a predetermined tolerance level. Aircraft control also includes the ability to use the four basics to position the aircraft in the landing pattern within another predetermined tolerance level of distance and altitude. The last element of aircraft control has to do with configuration. The pilot to select the optimum configuration for the situation uses wind and terrain. The so-called stabilized approach to landing begins far before turning final. The amount of tolerance allowed by an instructor is a variable based on how close you are to doing solo landings.
On downwind you should make a preliminary decision as to the flap configuration you will use. The POH standard is to land with full flaps if wind conditions allow. Just how you set the power, apply flaps, and trim for an airspeed is multi-task variable. Whatever you choose to do should have a consistency. Only in simulated emergency or short-short approaches should power be taken all the way off. Shock cooling the engine is a relatively dangerous practice. Whatever the power and flap setting the trim should be adjusted for the hands-off airspeed desired. Do not accept trimmed airspeeds off the desired speed. Most trainers use the same approach speed from the key position, to base, to final, to the round-out. Beyond the trainer, aircraft will use two or three different speeds from downwind, base, and final.
One variable that often occurs in downwind is an ATC call or situation that puts you as #3 to land or a need that you extend your downwind. In both cases you initiate the slow-flight procedure immediately even before using the radio. You want to avoid getting too far from the airport if possible. You hand-fly the slow-flight by using the same trim as you would have but add about 500 rpm to hold altitude and 10 degrees of flap to improve over the nose visibility. Resumption of the approach requires only reduction of power.
My preference is to reduce power to whatever setting will give me 1500 rpm when I reach the key position. The 'key' is a 45-degree angle to your rear toward the runway threshold. At the key position I will have maintained altitude and trimmed for my base approach speed, I put in one notch of flaps hold that airspeed with forward yoke and retrim while turning base. I have learned to put in flaps, apply forward pressure, and trim without looking any place except over the nose of the aircraft. I have begun my descent and am trimmed hands-off. Once my aircraft is under control I look to see the airport. A major fault of those who lose control is mixing up their priorities.
I make most of my approach adjustments on base. I may add a second notch of flaps, fly a wider base, or one closer in. Occasionally, ATC may ask you to make an adjustment by asking that you, "square your base" or "fly directly to the runway". Regardless of what you do, do it at a constant airspeed. Only by having a constant airspeed can you develop the skills needed in determining a stabilized approach angle. On final and on final approach airspeed I use the nose as a sight to make my high/low decisions. By aiming short of the runway a hundred feet you can become experienced in the use of ground effect. Being high offers the most corrective options; I can add flaps to maximum for wind conditions; I can reduce power in increments of 100 rpm or more; or, I can reduce my approach speed to cover less ground for altitude lost. Runway permitting I assume normal approach speed just prior to round-out. The universal solution for being low consists of adding full power while holding approach speed for an estimated time needed to intercept normal glide path.
Other opinions to the contrary, small additions of power can cause a pilot to enter into a condition known as 'the constantly decelerating approach'. As the power is added, the speed drops until there is not enough power to maintain altitude. You are behind the power curve and with the ground close by you have run out of options. The worst thing that could happen to a low-time pilot is to 'get away' with additions of power that lead to the decelerating approach. Next time you may not get away with it. (See decelerating approach)
Do, By Trying
Not To
From the very first flight we have been developing the skills
required for the successful performance of landing patterns. We
have learned the use of 90-degree reference points for making
turns. We have learned to use the heading indicator as a backup.
We have learned to hold altitude while changing airspeed. We have
learned to set power and trim for specific airspeeds. We have
learned to use trim for climbs, level, and descents. We have leaned
to control our airspeed while going through various flap settings.
We have learned to do the power off stall. We have learned to
do the go-around. We have learned to do these things while maintaining
an active scan outside the aircraft. Now, by putting all these
skills together in various combinations we can proceed with landings.
Other factors influence the 'putting together' of the landing skills. One such factor is the weather. The definition of the horizon can dramatically influence the ability of the student to level off at pattern altitude. The wind velocity and direction can make a student's pattern size and form become totally disrupted. A change in runways at the home field or a different runway layout at the new field can disorient a student. Nothing, but nothing, so disrupts the mental processes as being 'lost'. I am bringing this up early in the landing program because I want the student to be aware that flying the airplane is the first priority. Do not let the debilitating effects of disorientation so focus your attention and energies that you forget to fly the plane. It will happen if you let it happen. You can prevent it happening by flight preparation. You can prevent it by studying and knowing the area. You can learn to use the, properly set, heading indicator to resolve pattern difficulties. Do not let your efforts to make sure the runway is still in existence distract you from the essential of airspeed control. If, at any airport, you are unable to get down safely in three tries go elsewhere.
The conscious visualization of what is expected can actually cause it to occur. If the student can visualize the entire landing procedure both as to attitude, airspeed, sound and orientation about the runway it will happen. This is not the same as the oral/physical review of the skills and techniques involved. Rather, it is a mind's eye view of what is supposed to happen. Watch the way birds land on the ground or water. That is the way an airplane is supposed to land. With nose up and wings outstretched and curled down. The harder you try not to land, the better your landing is likely to be.
You can only keep ahead of an airplane by never getting behind. Trite but true. Many pilots have found that by saying orally the things they are doing and the things that they expect to happen. Example: "Trim down three, holding heading? and altitude?. What's next?" as would occur at the numbers on downwind. The system of self-direction and auto-interrogation works at all levels of skill and flying. Landings, because of their intellectual and emotional intensity, tend to become an area of ingrained habits. Some of these acquisitions are bad. These habits may be acquired from instruction, self-induced by poor practice, or acquired from other pilots. The unlearning of a bad habit is the most difficult process in flying.
The student should be made to realize that all of the foregoing procedures are, when arranged in a given sequence, the landing process. For a landing the airspeed must be made to transition smoothly from cruise, to approach, to stall. There may be a sequence of turns either left or right while descending. The trim and flaps must be smoothly coordinated in application to maintain the approach angle and speed. Power is smoothly changed from cruise to 1500 to off. The power off stall at moment of ground contact is the landing.
Using anticipation
Regardless of geographic points, wind conditions, power or
flaps the basic landing procedure is constant. As skills develop
the basic procedure may be varied to account for specific conditions.
The more constant your power, airspeed, angle of bank, control
touch, and stabilized approach the better we deal with the unexpected.
Again, the most important element of a good approach is to be
at the proper speed, trimmed for that speed, and at a pitch attitude
that will keep that speed. It is the trimmed pitch attitude that
keeps a speed constant or returning to a constant. If the pitch
attitude is right, even in gusty conditions, the speed will be
trying to return to its trimmed value. Instinctive reactions to
the sense of falling, hitting the ground, slips and turbulence
must be replaced with an understanding of what works.
Abruptness on the yoke will cause fluctuation of the airspeed and a widely varying climb, descent and altitude. Smoothness, anticipation, and a light touch give the very best in aircraft control.
Once the basic constants have been mastered, proficiency training will provide variations of flaps, power, approaches, and landings. We will land in widely differing winds with no flaps to full flaps. This teaches us to explore the outer performance limits of the aircraft as mated to pilot capability. Power will be varied as well. The short approach will be compared to the short-short approach. Ever try a simulated short-short approach to a short field landing on a muddy field? You may need to someday. For this reason it is important to your future success and safety that you be exposed to as much variation in procedures and situations as possible.
Ground
Effect
Ground effect makes it possible for an airplane to fly slower
close to the ground than would be possible even slightly higher.
Less induced drag is produced when the nearness of the ground
restricts airflow patterns around and below the wing. The airflow
above and below and wing is not symmetrical. The influence of
the ground slows the air across the bottom of the wing. This increases
the pressure differential and thereby the lift. It is this pressure
differential that gives lift. At a wingspan distance above the
ground this lift increases the closer to the ground you get.
Ground effect makes it possible to lift off at reduced speed and at too high pitch angles. If you leave ground effect you may be behind the power curve. This means you cannot accelerate without lowering the nose. If you can't lower the nose because of terrain you have run out of options.
Ground effect, when properly used, is a positive factor in soft field, density altitude takeoffs and low level go-arounds. Do not try to climb out of ground effect until you have attained climb speed. This speed is required at greater than wingspan heights to replace the less than wingspan height effects of the ground. Ground effect increases the closer you are to the ground. Low wing aircraft receive greater effect than high wing aircraft. The transitional difficulties that low-wing pilots have when moving to high-wing aircraft are caused by the significant differences in ground effect.
Ground effect is a tool to be used for all landings. It can cause good or poor landings. Properly used it allow a full stall landing at a ground speed slower than would be possible without ground effect. If the approach speed is too fast, the ground effect will cause float problems. Excessive float may cause a pilot to lower the nose while still with excess speed sufficient to hold the main wheels off the ground while the nose wheel touches. This is a very dangerous condition called wheelbarrowing.
To truly realize the power of ground effect, I would urge every student and pilot to go for at least two glider rides. The first would be the standard 20-minute demonstration. A great experience in use of the rudder while 'boxing' the towplane. The second should be a simulated glider emergency by the instructor. I won't tell any more since it would spoil the experience.
The key factor of ground effect is, "How close is the wing to the ground." The closer to the ground you can get the wing the more dramatic the reduction in drag. Flaring too close to the ground can cause a 'bounce' or balloon without even touching the ground. If the wheels touch the ground the bounce is much more pronounced and should transition into a go-around.
A thirty-foot wing within three feet of the ground will have nearly a 50% reduction in induced drag. At seven feet the reduction will be 25%. A pilot having this knowledge can adjust his landing flare altitude according to the situation. If you have a need to bleed off speed quickly, flare a bit high; if the need is to float, as to reach a particular touchdown point, flare low. You should practice different flare altitudes at different temperatures and density altitudes so as to blend your skills with the capabilities of the aircraft.
The landing
A more difficult awareness problem for the student pilot is
keeping the nose parallel to the runway centerline with the rudder
while countering any side movement of the aircraft with ailerons.
If this establishment of a sideslip is not at the instinctive
level you will be getting it wrong. One corrective technique used
by experienced pilots is to use a correction and then immediately
take half of it out. This method of making two-step corrections
is something you might want to try only if you seem always to
be in reactive mode rather than the anticipatory. Being able to
correct your mistakes safely is part of the process.
Accept any touchdown point in the first third of the runway. Beyond the first third, go-around. Don't ever become too pleased of landing on the numbers. Pride goeth before the landing short. If low on approach, apply full power to intercept the correct glide path. Don't change your flap configuration below 200' AGL. Every yoke movement should be "back". Ideally every power change would be a reduction. Don't let yourself be hurried off the runway. Clean up the plane only after the roll out is well controlled or clear of the runway.
Landing
Stall
With the yoke full back, power off, and the runway out of
sight you should hear the stall warner just as touchdown occurs.
Even a relatively high flare in this configuration will keep the
plane on the ground after initial contact. The main gear springs
tend to 'squat' and absorb the shock without rebounding. The nose
gear compresses and rebounds sending the nose into the air. Again,
do not let the yoke go forward. Do not let the nose wheel touch
the ground. Where the plane stays on the ground just keep the
yoke back. IF the plane becomes airborne, GO AROUND.
The full stall landing is most easily accomplished when the aircraft is loaded near (not beyond) the aft center of gravity limit. This gives the elevators more sensitivity, reduces the pitch forward on the nose wheel and allows the nose to be raised more easily. With a proper approach speed, power, roundout, and flare the full stall landing is likely to occur.
Touchdown
It is psychologically difficult for the student pilot to make
the runway disappear. An old PTS guide once said that the ideal
landing occurred when at the moment of touchdown, the yoke was
all the way back, the power was reduced to off, and the stall
warner would bleep. As the pilot you are striving for this ideal.
It does not occur often. The flare and landing is an act of faith.
You must believe that the runway will be there. You will not know
just when the landing will occur.
With the yoke full back, the power off, and the runway out of
sight you should hear the stall-warner just as touchdown occurs.
Even a relatively high flare in this configuration will keep the
plane on the ground after initial contact. At touchdown KEEP backpressure
on the yoke. Bring up the flaps and remove carburetor-heat. Maintain
runway heading. This allows the nose wheel to come down and the
plane to decelerate smoothly. Once you have made a good well-controlled
landing and have FAITH, each subsequent landing will seem easier.
The perfect touchdown to a landing is a very satisfying experience
and a cause of emotional release but!!!! Don't let the sudden
and perhaps hard ground contact permit the yoke to go forward.
Keep the yoke held full back and up. Directional control on roll
out is just as crucial though not as satisfying. Keep the plane
running true, don't apply brakes until flaps are raised. When
you are tied-down the landing is over.
Post-Landing
Techniques
There is some argument as to the best operation of flaps after
landing. Because of a proclivity for gear retraction accidents
to occur to those pilots who practice bringing up flaps on landing.
(They use the gear lever instead of the flap lever). Advise the
tower prior to landing if for any reason you can anticipate not
being able to clear the runway in a normal fashion. Don't let
yourself be hurried into clearing if it is not safe to do so.
In landing you OWN the runway.
However, there are wind conditions when the ground control of the aircraft necessitates getting the flaps up as soon as possible. Also there is a tendency for many pilots to apply brakes with the flaps down in such a manner as to lock the tires or to skid. The aerodynamic lifting of flaps, even under a light wind, is such that tire damage can result.
Recommendations have been made that flaps be left down until clear of the runway and stopped. For the first 25% of your rollout speed you will find that the flaps provide considerable drag and slowing effect. In line with the learning law of primacy such a practice has much to recommend it. Do not apply braking until you have started the flaps up. Do your heaviest braking while going straight ahead. Avoid heavy braking in turns. Keep the aircraft rolling to clear the runway.
The practicality of economics says to bring up the flaps on touchdown. If the landing shock causes the pilot to allow the yoke to move forward, the flaps can cause a condition known as 'wheelbarrowing'. This means that the lift from the flaps when added to the yoke position is sufficient to lift the main wheels off the pavement. This means the only ground contact is the nose wheel. Such a 'wheelbarrow' condition results in instant loss of control and a ground loop (very sharp turn). There are many landing situations where the yoke is held still or moved back and up. There are none where the yoke should be moved forward after touchdown.
The most efficient braking is pressure applied sufficient to almost stop the wheel from rolling while proceeding in line with your inertia. Any swerve or turn will reduce braking effectiveness and impose severe side loads on the aircraft and landing gear. Once the flaps are off the brakes become more effective due to the aircraft weight on the wheels. Holding the yoke back during braking will keep weight off the nose wheel and on the mains and inhibit nosewheel shimmy. Intermittent braking is not considered a viable alternative. Wait until you are clear of the runway (across the hold bars) to clean up the cockpit.
Salvaging
the Landing:
How do you know how and when to salvage a landing? Can some poor
approaches and flares be safely corrected? The answer is yes.
You must have very deep pockets to afford salvaging landings.
As previously indicated. Your best option will be the go-around.
Judicious additions of power may be applied and be successful.
A combination of luck and experience may work. My recommendation
is that all salvage efforts be delayed until you are using your
own airplane.
If ground contact is made before the yoke is fully back, then the airplane will still have some residue of flying speed left. On ground contact the plane may well become airborne again. Any touchdown at more than the slowest possible speed is hard on the plane. If the power has not been taken off at touchdown the likelihood of becoming airborne is greatly increased. If, under the foregoing conditions, yoke pressure is applied forward so as to keep the nose wheel in ground contact, wheelbarrowing may occur. The slightest swerve becomes instantly uncontrollable and will cause a ground loop or worse. GO AROUND.
The normal landing in a C-150 calls for full flaps. There is a nominal five-knot decrease in approach speed with the use of flaps to be used for short field landings. The steeper approach allowed by flaps greatly improves landing accuracy. The manual of the C-150 specifically prohibits slips with flaps. This is because it is possible for the flaps, especially full flaps, to block the flow of air to the horizontal stabilizer and elevator. Such a blockage can cause these flight surfaces to stall. This results in an abrupt and extreme nose down pitch. Like straight down. This is most likely to occur in gusty or wind shear conditions. Use minimum flaps when the wind is strong.
Actually, the wind has an influence not so much on airspeed as on the glide path angle and rollout distance. A wind can be considered a factor on landing rollout distance only if it exceeds 10% of your touchdown speed. A tailwind has the same effect that carrying excess approach speed would have. A landing touchdown with ten knots excess airspeed and a ten-knot tail wind will double the landing rollout distance required. A calm wind, less than five knots, has no significant effect on landing distance. For a headwind greater than 10% of touchdown speed subtract the percentage that the headwind is of the touchdown speed (CAS) from 90% and use the difference as a multiple of the now-wind roll-out distance. If your touchdown speed is 80 knots and the headwind is 16 knots and a no-wind landing distance is 2000 feet it works out as 90% - 16/80 = 90% -20R = 70% x 2000 = 1400 feet estimated roll-out distance. You can use the same calculations for a tailwind by just doubling the result. Close enough for government work.
Once a decision is made on final to land, the aircraft is slowed to Vref. The speed used for over-the-fence is called Vref. This is the speed used in ground effect and flare as power is gradually reduced. This speed is obtained by using Vso as adjusted for weight below gross plus 1/2 velocity of any wind gusts occurring. The resulting speed will be close to landing speed required to prevent hydroplaning on a wet runway. The lower the landing speed the shorter the landing distance. Landing with a higher than Vref in long-winged planes greatly increases float. Landing with a lower than Vref speed in short-winged aircraft will cause the plane to run out of ground effect sooner than desired. All landings are predicated on flying to the missed approach/go-around point before a landing decision is made.
Landing distance is a function of landing ground speed. Approximately 30% of the square of the landing speed gives the landing distance using English measurements. Thus a 70 mph approach (70 x 70 x .3 = 1470) will require approximately 1500 feet from over the fence altitude landing distance. Multiply the indicated Vref landing speed less any headwind component by itself, multiply this product by .3 and we have the expected landing distance to be slightly over 1000 feet. This landing distance assumes crossing the threshold at 50 feet and normal braking. Increasing the Vref by 10% will result in a 20% increase in required distance. If a 10-knot tail wind exists, the required distance will increase by 50%. A tail wind flattens the approach angle although the increase in speed may not be apparent until relatively close to the ground. A 10% reduction in POH Vso weight will give a 5% reduction in landing distance. Thus, a solo student should expect and plan for shorter landings.
As mentioned in the beginning, the 1.3 Vso can be used except in gusting conditions. All pattern airspeeds should be increased in gusting conditions. Any increase in airspeed should be half the gust factor as given, forecast, or estimated.
Straight in approaches to an upslope runway will cause the pilot to undershoot. A downslope will cause an overshoot. The best way to avoid the illusions caused by this, is to fly a full pattern. Being ground shy can be overcome by flying along a very long runway in slowflight.
Landing
speed
I find it unfortunate that so many POH presentations give
landing speed as a ten-knot range. Given a free choice the inexperienced
will chose the high end of this range as a 'safety factor. This
is wrong for several reasons:
-- POH speeds are for gross weights. It is only infrequently that planes are flown at full gross weights. Even at gross weights the low end of the POH approach speed is perfectly safe. What's more, for every 10% that you are below gross weight you can reduce the approach speed by 5%. In gusty conditions add half of the maximum gust speed.
-- Excess approach speed is only appropriate when it is required for nose alignment during crosswind landings. Otherwise, this speed must be dissipated while over the runway. This means floating and braking. Floating is wasteful of runway length unless done purposely to reduce taxi time. Braking tends to be hard on the aircraft. In some aircraft such as the taper-wing Pipers, excess speed may preclude even landing. If you are below gross fly the approach at Vref. Vref is the speed you figure based upon your weight as it actually is below gross.
Glide
Speeds
Power on or power off there are several recommended descent
gliding speeds for an aircraft. Once an aircraft is on a stabilized
flight path with a constant power just making a change in the
airspeed will change the glidepath. The aircraft can be trimmed
at any number of different glide speeds. One speed is considered
the dividing line between the front and backside of the power
curve. This speed is the speed usually used for an approach. Any
faster speed will increase the rate of descent and speed and the
distance covered. Any slower speed will cause a drop in airspeed
and an increase in descent rate covers less distance. The slower
speed is often used when an approach is very high. Maximum recommended
flaps, power off, and the slow speed to increase the descent rate
over less distance usually precede it. The same descent rate could
be achieved by lowering the nose and increasing the speed. The
increase in distance traveled would probably require a go-around
in lieu of a landing.
A blending of yoke and throttle can stabilize the actual flight path. The use of a constant throttle setting, even to off, makes the trimming for a constant, hands-off, airspeed the final ingredient for a stabilized approach.
Without flaps, an airplane gliding as the minimum sink airspeed vs. the maximum distance speed will give a .5-mile less distance for every 3000 feet of altitude. A glide cannot be stretched beyond the maximum glide distance. You can reduce the rate of sink but you will also reduce the distance. The heavier the plane the higher the speed needed to get the best glide ratio. Stopping the propeller by initiation a stall will make a significant increase in glide distance. With GPS it is relatively easy to determine the best glide speed for a specific weight and aircraft.
Touchdown
speed
The landing distance required of a given aircraft will approximate
30% of the square of the touchdown speed. A 10% increase in touchdown
speed will result in over a 20% increase in landing distance.
Flying an incorrect and higher speed as Vref will require a substantial
longer roll out.
The one speed required for landing that was not included in all prior instruction is the touchdown speed. We enter the flare at approach speed and make a slow deceleration to the variable full stall speed that precedes touchdown. This full-stall touchdown-speed is the one that best utilizes runway length, softens ground impact, and gives the lowest possible side loads on the landing gear.
Some runways and areas cause unfamiliar pilots to land long. Unfamiliar pilots tend to add excess airspeed where none is required. The slope of the runway and terrain may present visual images that are deceptive. It is always best to fly a standard pattern using standard procedures and a stabilized approach in strange situations. Trying to force the landing will cause excess speed at touchdown. This will dramatically increase the rollout distance. A 10% increase in touch down speed will increase the ground roll by the square of this factor amounting to 20 or more percent in required distance.
Landing
roll
The book figure for landing roll can be reduced by half the
percent reduction from gross landing weight. A 10% reduction in
weight will result in a 5% reduction in landing roll. If we reduce
our Vso approach speed by 5% we can expect to obtain about twice
that reduction in required landing distance.
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