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Learning to Land

On approach for runway 34, CYBW

One of the hardest thing in flying is learning to land.  When I was struggling with the landing, my instructor made me feel better by letting me know this, and saying that she didn’t really “learn” how to land until she was doing her commercial license.  Of course she knew how to to it, but by that she meant that she didn’t really feel fully comfortable until then.

This put a few things into perspective, how long it will take until not only will it feel natural but you will not be so terrified and dry-mouthed every time you do it.  Since my first solo flight, I have really started paying attention how to possibly make the best landing happen consistently.  I haven’t been flying in the circuit much lately, so each flight I only get to do one of these landings so I try to make it as good as possible.

The landing sequence. This plane is about to flare.
The landing sequence. This plane is about to flare.

One of the things that is very apparent is the amount of right rudder needed.  As you cut power to idle, and flare, you are operating the aircraft at very low power settings. Asymmetric thrust will cause the aircraft to want to yaw to the left: recall that the aircraft has left-turning tendencies which cause left yaw. This is actually what I noticed very clearly on my first solo flight, thinking it was the wind that was causing my nose to yaw to the left on landing, my instructor quickly corrected me that it was not using enough right rudder.

Four things will cause left -turning tendency. These are:

1. Torque reaction from engine and propeller

2.  Slipstream causing a corkscrewing effect of air hitting the tail on the right, yawing the aircraft to the left.

3.  Gyroscopic action of the propeller, the propeller is a gyroscope and tries to “spin” the aircraft the opposite way.

4.  Asymmetrical loading of the propeller at high nose attitudes.

On landing, asymmetric thrust causes the left yaw.  When you touch the ground, be prepared to add even more right rudder. The engine torque will cause the left wheel to carry slightly more weight than the right, increasing it’s drag and causing even more yaw to the left.

So how can you strive to make each landing perfect? I’ve made a list of steps that I think are very important to note:

1.  Check winds. When flying in the downwind leg, when on final, or whenever you get a chance note the windsock so you know what winds you will be experiencing on the ground and on your final approach. Will you have a crosswind?

2.    Approach at a constant airspeed for your configuration (whether using flaps or not), do not “chase” the airspeed: that is, do not focus your attention on the airspeed indicator and try to correct deviations by switching attitudes.  Establish your airspeed well in advance on final, note how the horizon looks when you have reached the proper airspeed, and keep it there. Once you have your airplane in the right attitude, keep it there.

3.   Pick a spot on the runway. When you stare at this spot, this is where you will flare. It also allows you to break down your desired touchdown spot and keep you from focusing on the entire runway.

4.  Flare 5-9 meters (15 to 30 feet) from the ground.  Over time, you will “sense” where this point is. I learned that to recognize this point is to when the movement of the ground suddenly becomes very apparent, the whole landing area seems to expand, and the point where the ground seems to be coming up so rapidly that something must be done about it.

5.  Once you flare, wait for the sink.  You are trying to bleed off airspeed.  Once you feel the sink, pull back more, just don’t pull back more before you feel the sink. This will cause the aircraft to balloon – gain lift – and the high nose attitude can cause you to stall when still too high above the ground resulting in a hard landing.   You need to cover up the runway with the nose of the aircraft to get the proper high nose landing attitude.  It will feel uncomfortable at first – it did for me.  This will allow you to avoid touching down with your nose gear, or having a ‘flat’ (three wheel) landing, which increases the risk of wheelbarrow. Pull back slightly each time you feel a sink, this will allow you to check your rate of descent until all flying speed is lost and you can touch the runway as lightly as possible.

6. Get in the habit of keeping your hand on the throttle throughout the landing. If something happens, for example if the landing is not going well and you need to overshoot or if there is something else wrong and you require application of power, the time to get this power if your hand was not on the throttle is too long.

There are four different kinds of landings:

  1. Normal landing
  2. Cross-wind landing; where wind inputs will be needed
  3. Short field landing, and
  4. Soft field landing.

We learn each landing and we practice all of them until they present no difficulty.

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The ‘six-pack’ flight instruments: gyroscopes

Continuing on our review of the ‘six pack’ of flight instruments from the instruments that are powered by the pitot-static system, below we review those that are gyroscopes.

A gyroscope is a rotor or spinning wheel rotating and high speed,  and exhibits two fundamental characteristics upon which all practical applications are based.  These are:

  1. Gyroscopic intertia –  or rigidity in space. This is the tendency of the rotating body to maintain it’s plane of rotation if undisturbed.
  2. Precession: This is the tendency of the rotating body, when a force is applied to it at a point perpendicular to the plane of rotation to react as if the force had been applied 90 degrees in the direction of rotation

The three gryroscopic instruments are:

  1. The heading indicator. The main instrument we use to detect heading of the aircraft.  Only operates when the engine is running.  It runs off a vacuum system so we have to adjust it to the magnetic compass every time we fly. Frictional forces in the gyro bearings cause it to precess, resulting in a creep or drift in reading approximately 3 degrees every 15 minutes.
  2. Turn and bank coordinator, sometimes called the needle and ball.  The needle shows the direction and approximate rate of turn. The ball shows the amount of bank in the turn and whether there is any slipping or skidding. The ball is controlled by gravity and centrifugal force.  In a coordinated turn, the ball will be in the center as the centrifugal force offsets the pull of gravity. The instrument reacts to yaw but can be used for roll control since the aircraft yaws when banked.  It can show a rate one turn which gives us 3 degrees per second or a two-minute turn.
  3. The attitude indicator. Modern attitude indicators have virtually no limits of pitch and roll and will be accurate indicate pitch up to 85 degrees, and will not ‘tumble’ in 360 degree rolls.

The instruments are typically powered by the vacuum system and an electrical system for redundancy in case one of the power sources fails.  Often the heading indicator and attitude indicator operate on the vacuum system while the turn and bank coordinator is electrically operated.

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The “six pack” flight instruments: pitot-static

Flight instruments on a Cessna 172

Let’s do a review of the six main flight instruments: 

Detail is provided, of course, there is so much more we can add here!  The most important and basic flight instruments have remained the same for a long period of time, and are called the ‘six pack’.  Three of them are connected to the static port system which measures outside barometric pressure and the pitot tube which measures ram pressure.   The other three are gyroscopic.

The Pitot Tube on a Cessna 172
The Pitot Tube on a Cessna 172

The pitot tube, located on the leading edge of the wing, and the atmospheric pressure in the tube is increased by the dynamic pressure due to the forward motion of the aircraft while in flight.  The static pressure port is not affected by turbulence or ram air pressures.

The three instruments connected to the pitot-static system are:

(1) Airspeed Indicator (ASI) – pitot and static source; it measures the difference between the pressure in the pitot tube and the pressure in the static system. When the aircraft is on the ground the two pressures become equal, in motion the pressure difference causes the aneroid capsule inside the indicator to expand, moving the needle on the instrument.

The ASI shows indicated airspeed.  Indicated airspeed can be erroneous because of air density, which depends on pressure and temperature, and position error, which is caused by eddies that are formed when air passes over the wings and struts. This is the uncorrected reading from the dial and calibrated airspeed is the indicated airspeed corrected for position error (and installation error). Equivalent airspeed is the calibrated airspeed corrected for compressibility – this applies mainly to high speed airplanes.  Next we have true airspeed which is calibrated airspeed corrected for pressure and temperature. Roughly, to correct calibrated airspeed we add 2% to the indicated airspeed for every 1000 feet of pressure altitude.  We can gain more accurate readings using our flight computer – the E6B.

(2) Vertical Speed Indicator, static source. Operates on the principle that there is a change of barometric pressure with a change in altitude.  Atmospheric pressure is led into the capsule but slowed by a calibrated leak from entry into the case holding the capsule,  and this pressure differential causes the capsule to expand or compress.  There is a 6-9 second lag before it will indicate the correct rate of climb or descent.

(3) Altimeter, static source. Since pressure varies from place to place and the altimeter set to indicate height above sea level at the departure point may give a false reading after the aircraft has flown some distance.  To correct for this, the altimeter is equipped with a barometric scale (inches of mercury) which allows to set the current altimeter setting. We get this each time we depart our airport and can get it enroute.  If we fly to an airport that has a lower pressure than the one we departed from and we don’t change our altimeter setting, we will read higher than the actual height of the airplane. Temperature differences will also cause erroneous readings since the pressure altimeter is calibrated to indicate true altitude in standard atmospheric conditions.  When the temperature of the air beneath the airplane is colder than standard, the aircraft is lower than indicated, and vice versa for warmer than standard temperatures (higher than altimeter reading) .

Here are what we can expect from a compromised static-port system.

Instrument Pitot Tube Blocked Partially Blocked Static Port Fully Blocked Static Port
Altimeter Not connected Under-read in climb, over-read in descent Freezes
Vertical Speed Indicator Not connected Under-read in climb, less than true rate of descent Freezes at 0
Airspeed Indicator Acts like altimeter. Over-reads in climbs and under-reads in descents Under-read in climb, over-read in descent Under reads in climbs and over reads in descents.

Read about the other 3  instruments that are gyroscopes: the heading indicator, attitude indicator and turn and bank coordinator.

Do you have any other specialty instruments in your aircraft?

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The Soft Field Procedure

Before I learned precautionary and forced approaches, I learned about soft field landings.  Here my account of the experience, and why soft fields are important and should be practiced regularly.

When will we use a soft field landing?

If we are planning to land on an unprepared surface. We also need to know the technique if we need to make a precautionary or forced landing, and have to put our airplane down in a field.

Like the short field procedure, the soft field is a lot of fun.  It is used when taking off and/or landing on an unprepared surface. The can be a grass strip or turf runway, or a completely unprepared runway.  One of the main goals is to protect your propeller and engine in the sequence. This means we try to keep it from being struck by flying debris and damaged, and to keep dirt and debris from being sucked into the engine.   It also is to keep the nose gear from diving into a hole – since it is an unprepared surface there may be lots of surface irregularities.  A small dip and we could wheelbarrow the plane.  We keep the nose high throughout the procedure as long as we can.

It starts during the taxi

Can I land my airplane in that field?
Can I land my airplane in that field, and what is the technique?

In fact, when we taxi on the unprepared runway we keep our control column full aft.  So when we pull up to line up on our runway we are pulling back as far as we can on the control column.  When we add power, we push forward slightly on the column until the airplane is ready to fly.  We rotate at about 46 knots with 10 degrees of flap in the 172 N model.

We fly in ground effect until we have built up enough airspeed to climb.  This is about 60 knots, so when we reach 60 knots, we pull up and climb out.  At 200′ AGL we announce that we have “two positive rates”

(1) altimeter increasing (showing a gain in altitude), and

2) vertical speed indicator increasing, and we retract the flaps and climb out normally at 70 knots.

Hold off on the landing

The airplanes POH will show us what speed to approach for our soft field landing.  In the 172, we use 61 knots.  The idea on the flare is try to hold off landing even longer than usual to keep the airplane nose high.  So after we flare and we feel the first “sink”, we add a bit of power, around 100 RPM or so and try to keep the airplane from touching down. We do so until we have run out of altitude, and the airplane will touch down very softly.  We keep the nose high to protect the propeller and keep from nose gear from running into rough terrain.

Soft field touch and go’s are probably the most fun of all – we do not push the nose down, and take off right away in a nose high attitude.  That means we stay off the nose wheel and just do a “wheelie” down the runway, and take off! In my solo I managed to make this happen a few times.

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The short field takeoff and landing with obstacle

Approach and landing over an obstacle

The next maneuver, after mastering the short field procedure, is doing so imagining  having to clear a 50 foot obstacle on both take off and landing. This is accomplished by imagining that there is a 50 foot obstacle at the end of our runway on the takeoff, and that there is a 50 foot obstacle on the start of our runway on the landing.

This short field takeoff and landing with obstacle procedure builds on the skills practiced in the short field takeoff and landing with no obstacle. The objective is to use as little  runway as possible to land and take off, but also to accurately plan our clearance point.  On the takeoff  we need to become airborne as soon as safely possible and climb as fast as possible so we clear our obstacle. This means we need to use Vx, our best angle of climb speed.

On the landing, we have to plan it so we approach so we clear the obstacle and at a proper speed so we still have enough runway to  stop.  The obstacle approach will have us touching down further down the runway then we would if we didn’t have an obstacle to clear, so we have less usable runway. We want to be at a slow enough speed commensurate with safety so we can stop with enough runway.

Ask for clearance

Since I fly out of Springbank airport, which is a controlled airport, I ask for a short delay on departure when I’m holding short of the runway.  In this procedure we line up at the very end of the runway – “on the button.”  Like the short field, we apply full brakes add full power, carb heat cold, check the engine and mixture (if required) and release the brakes.

The speed at which we rotate – or take off – will be given in the aircraft’s POH.  The POH will also give us the climb out speed. For the aircraft I learned on, GSKF, a Cessna 172 N, this is 46 knots. Note that the speed will change with respect to the aircraft’s weight – this is all given in the POH. The POH will also tell you if you need flaps or not for the procedure. For our aircraft I used 10 degrees of flaps.

Short field takeoff and climb with obstacle

Steeper climb-out angle

The main difference is we climb out at a much steeper angle than we did when we didn’t have an obstacle.  This causes the stall horn to sound – which I found disconcerting – but remember, the stall horn sounds 5-10 knots before the stall, so you will have time to ensure you control your speed, and on take-off, our speed is increasing, not decreasing.  Be aware, even though it takes a big longer to stall the aircraft at such high power settings, if you do, this is the dreaded departure stall.

Note clearing the obstacle

We need to mentally ‘note’ where the obstacle is, and to say “clear the obstacle’ once we have cleared it.  At Springbank, the altitude is 3940 feet, so once we are approximately at 4000 feet we announce we are clear the obstacle. The same follows, at 200 feet AGL we announce two positive rates and retract our flaps if we are using them.

More controlled, power-on approach required

The approach for landing is similar to the short field, with flaps – however the objective is to use a power on approach so once we reduce power to idle once we are are clear the obstacle.  We try not to approach too high initially so we decrease power to idle too soon – I made this mistake a few times while practicing, and on the flight test, the examiner wants to see that you know to decrease power once you are clear the obstacle, so they see you understand this is what you are trying to accomplish.

Once clear the obstacle which we imagine is at the start of the runway, we announce it, reduce power, and loose the last bit of altitude, flare and touch down. When we touch down, we push the nose down, retract the flaps, and add heavy brake while applying full back pressure with the control column.

Learning this procedure is challenging, but it is A LOT of fun!

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Short field landing

Short field landing and takeoff procedure explained

At a certain point, your lessons will be about precision flying after you know the basics.  Now my lessons are about more precise flying, not only just about making it down to the ground safely.  Recently I was practicing to aim to land at a particular spot on the runway, using different flap configurations and no flaps.  This was to get used to being precise and prepare for the short field landing technique.

The other day I learned the short field landing method. There are two kinds of short field procedures, with an obstacle (we usually use a 50 foot obstacle) and with no obstacle.  We did the landing without obstacle and next we will do with obstacle, as that is more advanced.   The non-obstacle technique assumes that the runway is clear of obstacles (such as trees or power lines) so we don’t have to worry about clearing anything on our approach or take off.

The short field landing technique is a lot of fun to learn and practice.  It is a specialty procedure that comes in handy when landing at an airport with an unknown runway length or when there are concerns about usable runway length.

We want to plan to use as little runway surface as possible to both take off and land. So on the take off, we line up “on the button” meaning as close to the runway edge as possible.

Short field takeoff

For the Cessna 172, and our particular model, and at Springbank airport, we then follow this takeoff procedure:

  1. Apply full brake
  2. Flaps 10 degrees
  3. Full power
  4. Lean the fuel mixture (check), then mixture full rich
  5. Confirm engine gauges in the green
  6. Release brakes

Once the aircraft starts to roll we steer with rudder to maintain runway centre line. Depending on the aircraft model, we lift off at the recommended speed to fly in ground effect. The particular aircraft we were in, FDAJ, this speed was 46 knots.  We pull up to fly in ground effect, and then push down on the control column to keep from climbing and keep the aircraft level. We fly in ground effect a few feet off the ground without climbing until the airspeed builds to 60 knots, at which point we pitch up and climb out at 65 knots.  We let the aircraft gain 200 feet of altitude AGL. At Springbank the above sea level altitude is 3940 ft, so we wait until our altimeter shows 4140 ft.  We then check for two positive rates on the instruments: one on the vertical speed indicator (VSI) and the altimeter – that is, the VSI is above zero which means the aircraft is in a climb, and that altimeter is increasing which also means the same. We take flaps to 0 degrees, that will establish our speed to 70 knots, and we climb out normally!

Short field Landing

Then there is the landing, which is followed by a full flap approach. In our aircraft we used 30 degrees of flaps and approached at 61 knots as recommended in the aircraft’s pilot operating handbook (POH). We wanted to plan to touch down 500-600 feet after we flared so we look for appropriate runway markers for us to judge this distance. At Springbank, runways 16 and 34 have 500 foot and 1000 foot markers, so it is easy to see our targets.

After we touch down, we apply the brakes – hard. We push the nose of the aircraft down for maximum brake effectiveness and retract the flaps to decrease the lift also to really make those brakes effective.  The first few times I landed I wasn’t aggressive enough on the brakes but eventually got to pushing down on them hard enough. The application of brakes should be so hard you actually are pushed forward and can feel your seat belt.  This is because we are trying to use the minimum runway length possible.

It was really a lot of fun to learn this procedure and I’m excited to try this next time, this time I will be on my own.