Takeoffs and climbs from fields in which the takeoff area is short or the available takeoff area is restricted by obstructions require the pilot to operate the WSC aircraft at the limit of its takeoff performance capabilities. To depart from such an area safely, the pilot must exercise positive and precise control of attitude and airspeed so that takeoff and climb performance results in the shortest ground roll and the steepest angle of climb.
The achieved result should be consistent with the performance section of the AFM/POH. In all cases, the power setting, trim setting, airspeed, and procedures prescribed by the manufacturer should be followed.
In order to accomplish a short field takeoff and steepest angle climb safely, the pilot must have adequate knowledge in the use and effectiveness of the best angle-of-climb (VX) speed and the best rate-of-climb (VY) speed for the specific make and model of WSC aircraft being flown.
The speed for VX is that which results in the greatest gain in altitude for a given distance over the ground. VX is usually less than VY but greater than minimum controlled airspeed. It should be noted that this maneuver is not performed in normal situations. Flying at VX speed close to the ground in gusty winds can result in a stall with catastrophic consequences.
If clearing an obstacle is questionable, the WSC aircraft should be packed up and trailered away. If a pilot decides to perform a short field takeoff, then a number of factors can be optimized to contribute to a short field takeoff such as leaving your passenger and/or baggage in the area, waiting for favorable winds or lower density altitude, and picking the longest runway path with the shortest obstacle to clear.
However, if a short field takeoff is going to be performed and all possible factors have been optimized, the following procedure is provided. The procedure is similar to the normal takeoff but the following additional procedure is used for this maneuver.
Taking off from a short field requires the takeoff to be started from the very beginning of the takeoff area. The WSC manufacturer’s recommended specific trim setting should be set before starting the takeoff roll. This permits the pilot to give full attention to the proper technique and the aircraft’s performance throughout the takeoff.
Some authorities prefer to hold the brakes until the maximum obtainable engine revolutions per minute (rpm) is achieved before allowing the WSC aircraft to begin its takeoff run. However, it has not been established that this procedure results in a shorter takeoff run in all WSC aircraft, many of which can not hold the brakes at full throttle. If the brakes are not held with the throttle advanced to full and then released, takeoff power should be applied immediately to full throttle as fast as possible without the engine bogging down to accelerate the aircraft as rapidly as possible. The WSC aircraft should be allowed to roll with the wing finding the trim position for minimum drag during acceleration to the lift-off speed.
Lift-Off and Climb Out
At VX speed, the WSC aircraft should be smoothly and firmly rotated by applying control bar forward pressure to an attitude that results in the VX airspeed. After becoming airborne, a wings-level climb should be maintained at VX until obstacles have been cleared. Thereafter, the pitch attitude may be lowered slightly and the climb continued at VY speed until reaching a safe maneuvering altitude.
Remember that an attempt to rotate off the ground prematurely or to climb too steeply may cause the WSC aircraft to settle back to the runway or into the obstacles. Even if the aircraft remains airborne, the initial climb remains flat and climb performance/obstacle clearance ability is seriously degraded until VX airspeed is achieved. [Figure 7-10]
In addition to normal takeoffs, common errors in the performance of short field takeoffs are:
- Deciding to do a questionable short field takeoff when the WSC aircraft can be packed up and driven away.
- Failure to adequately determine the best path with the longest run and shortest obstacle.
- Failure to utilize all available runway/takeoff area.
- Failure to wait for the best atmospheric conditions of density altitude and wind direction.
- Failure to reduce all possible weight from the WSC aircraft.
- Failure to have the WSC aircraft properly trimmed prior to takeoff.
- Premature lift-off resulting in high drag.
- Holding the WSC aircraft on the ground unnecessarily.
- Inadequate rotation resulting in excessive speed after lift-off.
- Inability to attain/maintain best VX airspeed.
- Fixation on the airspeed indicator during initial climb.