When performing takeoffs and climbs from fields where the takeoff area is short or the available takeoff area is restricted by obstructions, the pilot should operate the airplane at the maximum limit of its takeoff performance capabilities. To depart from such an area safely, the pilot must exercise positive and precise control of airplane attitude and airspeed so that takeoff and climb performance result in the shortest ground roll and the steepest angle of climb. [Figure 1] The pilot should consult and follow the performance section of the AFM/POH to obtain the power setting, flap setting, airspeed, and procedures prescribed by the airplane’s manufacturer.
|Figure 1. Short-field takeoff|
The pilot must have adequate knowledge in the use and effectiveness of the best angle-of-climb speed (VX) and the best rate-of-climb speed (VY) for the specific make and model of airplane being flown in order to safely accomplish a takeoff at maximum performance.
VX is the speed at which the airplane achieves the greatest gain in altitude for a given distance over the ground. It is usually slightly less than VY, which is the greatest gain in altitude per unit of time. The specific speeds to be used for a given airplane are stated in the FAA-approved AFM/POH. The pilot should be aware that, in some airplanes, a deviation of 5 knots from the recommended speed may result in a significant reduction in climb performance; therefore, the pilot must maintain precise control of the airspeed to ensure the maneuver is executed safely and successfully.
Taking off from a short field requires the takeoff to be started from the very beginning of the takeoff area. At this point, the airplane is aligned with the intended takeoff path. If the airplane manufacturer recommends the use of flaps, they are extended the proper amount before beginning the takeoff roll. This allows the pilot to devote full attention to the proper technique and the airplane’s performance throughout the takeoff.
The pilot should apply takeoff power smoothly and continuously, without hesitation, to accelerate the airplane as rapidly as possible. Some pilots prefer to hold the brakes until the maximum obtainable engine revolutions per minute (rpm) are achieved before allowing the airplane to begin its takeoff run. However, it has not been established that this procedure results in a shorter takeoff run in all light, single-engine airplanes. The airplane is allowed to roll with its full weight on the main wheels and accelerate to the lift-off speed. As the takeoff roll progresses, the pilot must adjust the airplane’s pitch attitude and AOA to attain minimum drag and maximum acceleration. In nose-wheel type airplanes, this involves little use of the elevator control since the airplane is already in a low drag attitude.
As VX approaches, the pilot should apply back-elevator pressure until reaching the appropriate VX attitude to ensure a smooth and firm lift-off, or rotation. Since the airplane accelerates more rapidly after lift-off, the pilot must apply additional back-elevator pressure to hold a constant airspeed. After becoming airborne, the pilot will maintain a wings-level climb at VX until all obstacles have been cleared or; if no obstacles are present, until reaching an altitude of at least 50 feet above the takeoff surface. Thereafter, the pilot may lower the pitch attitude slightly and continue the climb at VY until reaching a safe maneuvering altitude. The pilot must always remember that an attempt to pull the airplane off the ground prematurely, or to climb too steeply, may cause the airplane to settle back to the runway or make contact with obstacles. Even if the airplane remains airborne, until the pilot reaches VX, the initial climb will remain flat, which diminishes the pilot's ability to successfully perform the climb and/or clear obstacles. [Figure 2]
|Figure 2. Effect of premature lift-off|
The objective is to rotate to the appropriate pitch attitude at (or near) VX. The pilot should be aware that some airplanes have a natural tendency to lift off well before reaching VX. In these airplanes, it may be necessary to allow the airplane to lift-off in ground effect and then reduce pitch attitude to level until the airplane accelerates to VX with the wheels just clear of the runway surface. This method is preferable to forcing the airplane to remain on the ground with forward-elevator pressure until VX is attained. Holding the airplane on the ground unnecessarily puts excessive pressure on the nose-wheel and may result in “wheel barrowing.” It also hinders both acceleration and overall airplane performance.
On short-field takeoffs, the landing gear and flaps should remain in takeoff position until the airplane is clear of obstacles (or as recommended by the manufacturer) and VY has been established. Until all obstacles have been cleared, the pilot must maintain focus outside the airplane instead of reaching for landing gear or flap controls or looking inside the airplane for any reason. When the airplane is stabilized at VY, the landing gear (if retractable) and flaps should be retracted. It is usually advisable to raise the flaps in increments to avoid sudden loss of lift and settling of the airplane. Next, reduce the power to the normal climb setting or as recommended by the airplane manufacturer.
Common errors in the performance of short-field takeoffs and maximum performance climbs are:
- Failure to review AFM/POH and performance charts prior to takeoff.
- Failure to adequately clear the area.
- Failure to utilize all available runway/takeoff area.
- Failure to have the airplane properly trimmed prior to takeoff.
- Premature lift-off resulting in high drag.
- Holding the airplane on the ground unnecessarily with excessive forward-elevator pressure.
- Inadequate rotation resulting in excessive speed after lift-off.
- Inability to attain/maintain VX.
- Fixation on the airspeed indicator during initial climb.
- Premature retraction of landing gear and/or wing flaps.