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Crosswind Takeoff

Introduction:

  • While it is usually preferable to takeoff into the wind, but most situations will not be a pure headwind and some crosswind component will exist
  • One example of where you may want to takeoff with a tailwind would be rising terrain, or perhaps if in a glider, a lack of landing options in a rope break
  • No matter what situation you have, always run the numbers and do not exceed the aircrafts limits

WARNING:
All procedures here are GENERALIZED for learning.
Fly the maneuver in accordance with the Pilot Operating Handbook (POH)
and/or current Standard Operating Procedures (SOPs)


Crosswind Component Chart
Figure 1: Crosswind Component Chart

Effect of Winds:

  • Headwinds:
    • Takeoff will require less distance:
      • Air is already flowing over the airfoils without any movement of the aircraft
      • Depending on the amount of wind and sensitivity of the airspeed indicator, this will register an airspeed without any aircraft motion
      • Because the aircraft feels as though it is already moving (by a factor of the headwind), takeoff lift will be achieved in less time
      • The endstate is that the aircraft will become airborne in less time which translates to less distance
    • Takeoff at slower ground speed
  • Effects of a tailwind:
    • Increased speed to develop minimum lift causing stress on tires
    • Increased takeoff distance
  • Crosswinds:
    • Crosswinds will have some component that is chord wise flow (over the wings) and span wise flow (from the wing tip to the wing root)
    • The chord wise flow will be either a headwind or tailwind as previously stated to help or hinder performance
    • The span wise flow will always be disruptive and provide nothing as the air is not flowing over the wings from leading to trailing edge

  • Prior to takeoff, you need to complete appropriate takeoff performance data for the crosswind you expect to encounter

Weight:

  • When an instructor is not in the plane, the pitch attitude may differ
  • The aircraft will be airborne sooner, climb more rapidly, and have higher performance

Wake Turbulence:

  • Large, heavily loaded, slow aircraft generate wake turbulence

747 Takeoff
Figure 2: 747 Takeoff/Wake Turbulence Generation

Crosswind Control Mechanics:

  • From takeoff you will need to compensate for wind blowing at an angle to the runway
  • Placing the yoke into the wind raises the aileron on the upwind wing, to impose a downward force on the wing, to counteract the lifting force of the crosswind and prevents the wing from rising
  • As speed increases, the control surfaces become more effective as you transition from a taxi to flying, thereby requiring less of an input to achieve the same effect, so you will need to take out inputs as you accelerate
    • The crosswind effect will never completely disappear so some input will remain
  • If when taking out your inputs the upwind wing is allowed to rise, it will expose more surface to the crosswind and a skipping action may result
    • This side-skipping imposes severe side stresses on the landing gear and could result in structural failure
  • As both main wheels leave the runway and ground friction no longer resists drifting, the airplane will be slowly carried sideways with the wind unless adequate drift correction is maintained by the pilot
  • If proper crosswind correction is being applied, as soon as the airplane is airborne, it will be side-slipping into the wind sufficiently to counteract the drifting effect of the wind
  • This side-slipping should be continued until the airplane has a positive rate of climb
  • At that time, the airplane should be turned into the wind to establish just enough wind correction angle to counteract the wind and then the wings rolled level
  • Allow the aircraft to weathervane as it rotates and the effect of the crosswind will diminish
    • This puts you at risk if you have too much of an input to have a potential strike with the wingtip and the ground, especially with a low-wing aircraft
    • Anticipate this by keeping the wings level and letting the airplane vane to achieve that straight ground track
  • If a significant crosswind or gusts exists, the main wheels should be held on the ground slightly longer than in a normal takeoff so that a smooth but very definite liftoff can be made
    • This procedure will allow the airplane to leave the ground under more positive control, so that it will definitely remain airborne while the proper amount of wind correction is being established

Trim:

  • Trimming the aircraft allows for the relief of control pressures to stabilize the aircraft
  • Rudder trim is the most common on general aviation
    • Rudder is trimmed right for power increases and slower airspeeds
    • Rudder is trimmed left for power reductions and higher airspeeds
  • Elevator trim:
    • Elevator is trimmed up for power reductions and slower airspeeds
    • Elevator is trimmed down for power additions and higher airspeeds
  • Aileron:
    • Used as required to level an aircraft
  • Trim Tabs:
    • Servo: trim tab moves opposite of the surface it is trimming
    • Anti-Servo: trim tab moves with the surface it is trimming

C-172S Procedure:

  1. Ensure that the Before Takeoff Checklists are complete
  2. Check wind direction indicators, as available, and listen to ATC's wind call when given clearance for takeoff
    • ATC: "[Callsign], [Wind], cleared for takeoff [Runway]"
  3. Check the approach path is clear and then taxi into takeoff position
    • Crossing the hold short call Lights (nav/strobe/landing), Camera (transponder), Action (mixture/flaps/trim/fuel pump, if required"
    • Utilize all runway possible
    • Roll forward slightly to straighten the nosewheel
    • Use full yoke to position the flight controls for existing wind conditions
  4. Smoothly and continuously apply full throttle, maintaining directional control and runway centerline with the rudder pedals
    • Applying power too quickly may yaw the aircraft to the left, due to torque, most apparent in high-powered engines
    • Lower feet to the floor (toes on rudders, not brakes)
  5. Check engine instruments, airspeed, and tachometer
    • ICS: "Engine instruments in the Green, Airspeed Alive"
    • Keep in right rudder and some left aileron to counteract p-factor crosswind effect in required
  6. As you accelerate, maintain centerline with the rudder and wings level with the aileron
    • Slowly remove aileron inputs as the control surface becomes more effective
    • As you accelerate, the aircraft must be flown and not taxied, requiring smaller inputs
  7. At Vr (55 KIAS), call out, "Vr, Rotate" and increase control yoke back pressure to pitch up until the top of the glare shield meets the horizon (approx. 9-10°)
    • Smoothly pitch up or the aircraft may delay a climb
    • Forcing the aircraft off the ground may leave it stuck in ground effect or stall
    • During gust conditions, the pilot should remain on the deck a little longer
  8. After liftoff, establish and maintain Vy (74 KIAS) while maintaining the flight path over the runway centerline
    • Trim as necessary
    • Use of the rudders will be required to keep the airplane headed straight down the runway, avoiding P-factor
    • The remainder of the climb technique is the same used for normal takeoffs and climbs
  9. With a positive rate of climb and no available landing area remaining, depress the brake pedals, call out, "Positive Climb"
  10. During climb out (no less than 200' AGL), lower the nose momentarily to ensure that the airspace ahead is clear, and then reestablish and maintain Vy, maintaining the flight path over the extended runway centerline
    • Trim as necessary
    • Avoid drifting off centerline or into obstructions, or the path of another aircraft that may be taking off from a parallel runway
  11. At 500' AGL, lower the pitch (approx. 7-8°) to establish and maintain a cruise climb (85 KIAS)
  12. Execute a departure procedure or remain in the traffic pattern, as appropriate
    • If remaining in the pattern, keep the auxiliary fuel pump on
  13. Complete the Climb checklist

Crosswind Takeoff
Figure 3: Airplane Flying Handbook, Crosswind Takeoff Roll and Initial Climb

Common Errors:

  • Failure to adequately clear the area prior to taxiing into position on the active runway
  • Using less than full aileron pressure into the wind initially on the takeoff roll
  • Mechanical use of aileron control rather than sensing the need for varying aileron control input through feel for the airplane
  • Premature liftoff resulting in side-skipping
  • Excessive aileron input in the latter stage of the takeoff roll resulting in a steep bank into the wind at liftoff
  • Inadequate drift correction after liftoff

Practical Test Standards/Airman Certification Standards:

  • Practical Test Standards/Airman Certification Standards
  • Private Pilot Airplane Land:
    1. Exhibits satisfactory knowledge of the elements related to a normal and crosswind approach and landing with emphasis on proper use and coordination of flight controls
    2. Considers the wind conditions, landing surface, obstructions, and selects a suitable touchdown point
    3. Establishes the recommended approach and landing configuration and airspeed, and adjusts pitch attitude and power as required
    4. Maintains a stabilized approach and recommended airspeed, or in its absence, not more than 1.3 VSO, +10/-5 knots, with wind gust factor applied
    5. Makes smooth, timely, and correct control application during the round out and touchdown
    6. Touches down smoothly at approximate stalling speed
    7. Touches down within the available runway or water landing area, within 400 feet beyond a specified point with no drift, and with the airplane’s longitudinal axis aligned with and over the runway center/landing path
    8. Maintains crosswind correction and directional control throughout the approach and landing sequence
    9. Executes a timely go around decision when the approach cannot be made within the tolerances specified above
    10. Utilizes after landing runway incursion avoidance procedures
    11. Completes the appropriate checklist
  • Private Pilot Airplane Sea:
    1. Exhibits satisfactory knowledge of the elements related to a normal and crosswind approach and landing with emphasis on proper use and coordination of flight controls
    2. Adequately surveys the intended landing area
    3. Considers the wind conditions, landing surface, obstructions, and selects a suitable touchdown point
    4. Establishes the recommended approach and landing configuration and airspeed, and adjusts pitch attitude and power as required
    5. Maintains a stabilized approach and recommended airspeed, or in its absence, not more than 1.3 VSO, +10/-5 knots, with wind gust factor applied
    6. Makes smooth, timely, and correct control application during the round out and touchdown
    7. Contacts the water at the proper pitch attitude
    8. Touches down within the available runway or water landing area, within 400 feet beyond a specified point with no drift, and with the airplane’s longitudinal axis aligned with and over the runway center/landing path
    9. Maintains crosswind correction and directional control throughout the approach and landing sequence
    10. Executes a timely go around decision when the approach cannot be made within the tolerances specified above
    11. Utilizes after landing runway incursion avoidance procedures
    12. Completes the appropriate checklist

Conclusion:

  • Takeoff (and landing) factors are dependent on: thrust, weight, lift, drag, and friction (runway surfaces)
  • After reaching the hold short and completing all checklists you are ready to call for takeoff clearance
    • If ever told to taxi off the active and you receive a subsequent clearance, ensure all takeoff checklists are performed AGAIN

References: