Air Exercise: CrossWind Landings

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Air ExerciseCross-Wind Landings
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Definition

• Landings with winds from any side.

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Why?

• Runways dont move and we cant control the winds.

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How (In brief)?

• Side-slip Modify normal approach procedures as
  follows. (FTM p. 107)
• Maintain flight path aligned with centre of the
  runway by crabbing.
• Before the flare and use the rudder to straighten
  the aircraft with the runway.
• Bank slightly into the wind with the ailerons.
• Airspeed should be 5-10kts higher than for normal
  landings.

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Cross wind landings Techniques (expanded)

• Crab method
• Wings lowmethod

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Crab method

• The crab method is executed by establishing a
  heading (crab) toward the wind with the wings
  level so that the airplane's ground track remains
  aligned with the centerline of the runway.
• This crab angle is maintained until just prior to
  touchdown, when the longitudinal axis of the
  airplane must be quickly aligned with the runway
  to avoid sideward contact of the wheels with the
  runway.

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Crab method (2)

• If a long final approach is being flown, the
  pilot may use the crab method until just before
  the roundout is started and then smoothly
  changing to the wing low method for the remainder
  of the landing.

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Wings low method

• To use the wing low method, the pilot aligns the
  airplane's heading with the centerline of the
  runway, notes the rate and direction of drift,
  then promptly applies drift correction by
  lowering the upwind wing.

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Wings low method (2)
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Wings low method (3)

• The amount the wing must be lowered depends on
  the rate of drift. When the wing is lowered, the
  airplane will tend to turn in that direction.
• It is necessary, then, to simultaneously apply
  sufficient opposite rudder pressure to prevent
  the turn and keep the airplane's longitudinal
  axis aligned with the runway.
• In other words, the drift is controlled with
  aileron, and the heading with rudder.

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Wings low method (4)

• The airplane will now be side slipping into the
  wind just enough that both the resultant
  flightpath and the ground track are aligned with
  the runway.
• If the crosswind diminishes, this crosswind
  correction must be reduced accordingly or the
  airplane will begin slipping away from the
  desired path.

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Strong crosswind

• To correct for very strong crosswind, the slip
  into the wind must be increased by lowering the
  upwind wing a considerable amount.
• As a consequence, this would result in a greater
  tendency of the airplane to turn.
• Since turning is not desired, considerable
  opposite rudder must be applied to keep the
  airplane's longitudinal axis aligned with the
  runway.

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Strong crosswind (2)

• In some airplanes, there may not be sufficient
  rudder travel available to compensate for the
  strong turning tendency caused by the steep bank.
• If the required bank is so steep that full
  opposite rudder will not prevent a turn, the wind
  is too strong to safely land the airplane on that
  particular runway with those wind conditions.

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Strong crosswind (3)

• Since the airplane's capability would be
  exceeded, it is imperative that the landing be
  made on a more favourable runway either at that
  airport or at an alternate airport.

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Flaps and crosswinds

• Flaps can and should be used during most
  approaches since they tend to have a stabilizing
  effect on the airplane.
• However, the degree to which flaps should be
  extended will vary with the airplane's handling
  characteristics, as well as the wind velocity.

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Flaps and crosswinds (2)

• Full flaps may be used so long as the crosswind
  component is not in excess of the airplane's
  capability or unless the manufacturer recommends
  otherwise.

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Cross winds and the flare

• Since the airspeed decreases as the flare
  progresses, the flight controls gradually become
  less effective as a result, the crosswind
  correction being held would become inadequate.
• When using the wing low method then, it is
  necessary to gradually increase the deflection of
  the rudder and ailerons to maintain the proper
  amount of drift correction.

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Cross wind flare (2)
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Ground Roll

• Special attention must be given to maintaining
  directional control by use of rudder, or
  nosewheel/tailwheel steering, while keeping the
  upwind wing from rising by use of aileron.
• When an airplane is airborne it moves with the
  air mass in which it is flying regardless of the
  airplane's heading and speed.
• However, when an airplane is on the ground it is
  unable to move with the air mass (crosswind)
  because of the resistance created by ground
  friction on the wheels.

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Cross wind landing roll (2)
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Ground Roll (3)

• Characteristically, an airplane has a greater
  profile or side area, behind the main landing
  gear than forward of it.
• With the main wheels acting as a pivot point and
  the greater surface area exposed to the crosswind
  behind that pivot point, the airplane will tend
  to turn or "weathervane" into the wind.

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Crosswind component

• Wind acting on an airplane during crosswind
  landings and takeoffs is the result of two
  factors - one is the natural wind which acts in
  the direction the air mass is traveling, while
  the other is induced by the movement of the
  airplane and acts parallel to the direction of
  movement.
• Consequently, a crosswind has a headwind
  component acting along the airplane's ground
  track and a  crosswind component acting 90
  degrees to its track.

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Crosswind component (2)

• The resultant or relative wind, then, is
  somewhere between the two components.
• As the airplane's forward speed decreases during
  the after landing roll, the headwind component
  decreases and the relative wind has more of a
  crosswind component.
• The greater the crosswind component the more
  difficult it is to prevent weathervaning.

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Wind Components
Wind 190/15 knots at SteinbachSouth with the
runways 35/17 How much of this wind is a head
wind and cross wind?
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Wind Components (2)

• ExampleWinds 190_at_15 knots a Steinbach South
  with the runways 35/17
• Chose runway 17, because the winds are reported
  out of 190, thus the winds are 20 degree of the
  runway.
• On the headwind side of the graph find 20 degree
  off the runway and move up the to the 20 knot
  arc.
• The point that the 20 degree line and the 20 knot
  arc meet look straight down and straight to the
  left.
• To the left is the headwind component and down is
  the crosswind component. Cross wind 7
  knotsHead wind 18 knots

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