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Soft Field Takeoff

Introduction:

  • Soft field takeoffs are used to obtain maximum performance when departing from a soft or rough runway surface
  • Otherwise "hard" surfaces can be made "soft" following rain storms or disturbance
  • These soft and rough surfaces provide unique challenges which may make the aircraft harder to control and reduce acceleration
  • Additionally, with soft and perhaps bumpy surfaces, you are at risk of getting the nose wheel stuck

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)


C-172S Procedure:

  1. Ensure the before takeoff checklists are complete and flaps set to 10°
  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]"
      • Example: "Cessna One Seven Two Seven Victor, wind two seven zero at one zero, cleared for takeoff runway two six"
  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, positioning the flight controls for existing wind conditions
    • Full yoke into the wind
  4. Without stopping the airplane, smoothly and continuously apply full throttle
  5. Check engine instruments and tachometer (RPM)
    • ICS: "Engine instruments in the green"
  6. Keep the nose wheel clear of the runway during the takeoff roll (approx. 2-3°), maintaining directional control and runway centerline with the rudder pedals
    • Lower feet to the floor (toes on rudders, not brakes)

    NOTE:
    Do not allow the airplane to pitch up excessively causing a tail strike

  7. As you start to roll, monitor your airspeed
    • ICS: "Airspeed Alive"
    • Keep in right rudder and some left aileron to counteract p-factor crosswind effect as required
    • As you accelerate, the aircraft must be flown and not taxied, requiring smaller inputs
  8. At Vr, call out, "Vr, Rotate" and increase control yoke back pressure to pitch up (approx. 6°-7°)
    • 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
  9. As the main wheels lift off the runway, lower the pitch attitude to establish and maintain a level flight attitude, while remaining in ground effect, and accelerating to obstacle clearance speed
    • With no obstacles:
      • Establish a Vy climb attitude
      • Establish and maintain Vy, while maintaining the flight path over the runway centerline
      • Trim as necessary
    • With obstacles:
      • Establish and maintain obstacle clearance speed (Vx) until all obstacles are cleared
      • Maintain the flight path over the runway centerline
      • Trim as necessary
  10. After liftoff, establish and maintain obstacle clearance speed until all obstacles are cleared (50' AGL), while maintaining the flight path over the runway centerline
    • Trim as necessary
    • Use of the rudders may 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
  11. With a positive rate of climb and no available landing area remaining, depress the brake pedals, call out, "Positive Climb"
  12. With obstacles cleared, lower the pitch to begin accelerating to Vy
  13. At or above 65 KIAS, retract the flaps to 0°
    • Establish and maintain Vy
    • 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
  14. During the climb out (no less than 200' AGL), lower nose momentarily to ensure that the airspace ahead is clear, and then re-establish Vy, while maintaining flight path over extended runway centerline
    • Trim as required
  15. At 500' AGL, lower the pitch (approx. 2-3°) to establish and maintain a cruise climb

  16. NOTE:
    Maintain Vy if climb performance warrants

  17. Execute a departure procedure, or remain in the traffic pattern, as appropriate

  18. NOTE:
    If remaining in the traffic pattern, leave the auxiliary fuel pump switch in the ON position

  19. Complete the climb flow/checklist, when appropriate

Soft Field Takeoff
Figure 1: Airplane Flying Handbook, Soft field takeoff

Common Errors:

  • Failure to adequately clear the area prior to taxiing into position on the active runway
  • Insufficient back-elevator pressure during initial takeoff roll, resulting in inadequate angle of attack
  • Failure to cross-check engine instruments for indicators of proper operation after applying power
  • Poor directional control
  • Climbing too steeply after liftoff
  • Abrupt and/or excessive elevator control while attempting to level off and accelerate after lift-off
  • Allowing the airplane to "mush" or settle, resulting in an inadvertent touchdown after liftoff
  • Attempting to climb out of ground effect area before attaining sufficient climb speed
  • Failure to anticipate an increase in pitch attitude as the airplane climbs out of ground effect

Practical Test Standards/Airman Certification Standards:


Case Studies:

  • NTSB Identification: WPR14CA009: The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot's decision to continue the takeoff from a wet and soft airstrip which resulted in his failure to maintain adequate airspeed and aircraft control during the takeoff initial climb

Conclusion:

  • Takeoff (and landing) factors are dependent on: thrust, weight, lift, drag, and friction (runway surfaces)

References: