Chapter 5: Takeoffs and Departure Climbs
About twenty percent of all general aviation (GA) accidents occur during takeoff and departure climbs. More than half are the result of some sort of failure of the pilot. Twenty percent of the mishaps are the result of loss in control of the airplane.
The takeoff and initial climb are relatively short phases required for every flight with a high accident rate. Becoming proficient, and applying the correct techniques and principles, will help pilots reduce their susceptibility to mishaps. Pilots should be consult the ground roll distances for take-off and landing, established in the Pilot's Operating Handbook (POH) or Airplane Flying Manual (AFM), to have a good estimate of the total runway needed to accelerate and then stop.
Elements of Takeoff and Climb
The takeoff and climb is one continuous maneuver. However, it can be divided into three separate steps for discussion:
Prior to Takeoff
Takeoff performance charts in the POH/AFM should be consulted prior to takeoff. This will predict performance and establish if if the airplane is capable of a safe takeoff and climb for the conditions and location. High density altitude is a common concern, since this will reduce engine and propeller performance, increase takeoff rolls, and decrease climb performance.
Due to the risk of wake turbulence, it is not recommended to take off immediately behind another aircraft. This is especially true if departing after large transport airplanes, which create large wingtip vortices. Wake turbulence can be avoided by remaining clear of the other aircraft's flightpath. It also can be avoided by rotating prior to the point at which the preceding aircraft rotated.
Normal takeoff is done with the airplane is headed into the wind. Since the airplane depends on airspeed, a headwind provides some of that airspeed even before the airplane begins to accelerate into the wind. A headwind also decreases the ground speed necessary to achieve flying speed, permitting the use of shorter runways while reducing wear and stress on the landing gear and tires.
If a tailwind takeoff is necessary, consult performance takeoff charts in the POH/AFM to confirm there is sufficient performance and runway length.
On takeoff, an abrupt application of power may cause the airplane to yaw sharply to the left because of the torque effects of the engine and propeller. As the airplane gains speed, rudder pressure is needed to correct for propeller forces and any wind. If the elevator is correctly trimmed, the elevator control tends to assume a neutral position. Aileron controls should be banked into any crosswind.
As airspeed increases, airflow increases over the airplane's control surfaces. Tail surfaces become effective first, due to propeller slipstream. Smaller rudder deflections are needed to maintain direction. The feel of resistance to the airplane controls indicates that the airplane has increasing controllability.
Student pilots may tend to move the controls through wide ranges, seeking the pressures that are familiar and expected. This can result in overcontrolling the airplane. The flight instructor must help the student learn proper response to control actions and airplane reactions. The instructor should always stress using the proper outside reference to judge airplane motion. Have the student pilot follow through lightly on the controls, feel for resistance, and point out the outside references that provide the clues for how much control movement is needed and how the pressure and response changes as airspeed increases.
The ideal takeoff attitude requires only minimum pitch adjustments shortly after the airplane lifts off to attain the speed for the best rate of climb (Vy).
When all the flight controls become effective during the takeoff roll in a nose-wheel type airplane, the pilot should gradually apply back-elevator pressure to raise the nosewheel slightly off the runway, thus establishing the takeoff or lift-off attitude. This is the "rotation" (around the airplane's lateral axis) for lift-off and climb. Note that each type of airplane has a best pitch attitude for normal lift-off.
Flight instructors should be aware that initially, the student pilot may have a tendency to hold excessive back-elevator pressure just after lift-off, resulting in an abrupt pitch-up. The pitch attitude necessary for the airplane to accelerate to Vy speed should be demonstrated by the instructor and memorized by the student.
As the airplane lifts off the surface, the pitch attitude to hold the climb airspeed should be held with elevator control and trimmed to maintain that pitch attitude without excessive control pressures. The wings should be leveled after lift-off. Rudder should be used to ensure coordinated flight and maintain the track of the airplane along the runway centerline.
It is important to hold the correct attitude constant after rotation or lift-off. If the airplane is forced to leave the ground by using too much back-elevator pressure before adequate flying speed is attained, the wing's angle of attack may become excessive. This will cause the airplane to settle back to the runway. A stall is possible.
However, if the correct takeoff attitude is not maintained after becoming airborne — or the nose is allowed to lower excessively — the airplane may also settle back to the runway.
As the airplane leaves the ground, the pilot must keep the wings in a level attitude and hold the proper pitch attitude. A novice pilot often has a tendency to fixate on the airplane's pitch attitude and/or the airspeed indicator and neglect bank control of the airplane.
Due to the minimum airspeed, the flight controls are not as responsive, requiring more control movement to achieve an expected response. Torque from the engine tends to impart a rolling force that is most evident as the landing gear is leaving the surface.
During takeoffs in a strong, gusty wind, the pilot should allow the airplane to stay on the ground longer to attain more speed. Takeoff at the normal speed may result in a lack of positive control (or a stall) when the airplane encounters a sudden lull in strong, gusty winds or other turbulent air currents.
Upon lift-off, the airplane should be flying at approximately the pitch attitude that allows it to accelerate to Vy — the airspeed at which the airplane gains the most altitude in the shortest period of time. Takeoff power be maintained until reaching an altitude of at least 500 feet AGL.
The pilot should not fixate on the airspeed indicator when making pitch changes, and instead should continue to scan outside to adjust the airplane's attitude in relation to the horizon. The airspeed indicator should be used only as a check to determine if the climb attitude is correct. Due to inertia, the airplane will not accelerate or decelerate immediately as the pitch is changed.
The climb pitch will be lower when the airplane is heavily loaded, or when power is limited by density altitude.
During initial climb, it is important that the takeoff path remain aligned with the runway to avoid drifting into obstructions or into the path of another aircraft that may be taking off from a parallel runway. A flight instructor should help the student identify two points inline ahead of the runway to use as a tracking reference.
When the student pilot nears the solo stage of flight training, it should be explained that the airplane's takeoff performance will be much different when the instructor is not in the airplane. Due to decreased load, the airplane will become airborne earlier and climb more rapidly. The pitch attitude may differ due to decreased weight. The flight controls may seem more sensitive
Common errors in the performance of normal takeoffs and departure climbs are:
The technique used during the initial takeoff roll in a crosswind takeoff is generally the same as the technique used in a normal takeoff roll, except that the pilot must apply aileron pressure into the crosswind.
While taxiing into takeoff position, it is essential that the pilot check the windsock and other wind direction indicators for the presence of a crosswind. If a crosswind is present, the pilot should apply full aileron pressure into the wind while beginning the takeoff roll. The pilot should maintain this control position, as the airplane accelerates, until the ailerons become effective.
The raised aileron on the upwind wing imposes a downward force on the downwind wing, which is closer to the wind. This counteracts the lifting force of the crosswind and prevents the downwind wing from rising.
Since the ailerons and rudder are deflected, drag will increase. Less initial takeoff performance should be expected when compared to a normal takeoff.
While holding aileron pressure into the wind, the pilot should use the rudder to maintain a straight takeoff path. Since the airplane tends to weathervane into the wind while on the ground, the pilot will typically apply downwind rudder pressure.
In a crosswind from the left to the right, left-turning tendency on takeoff may be sufficient to counteract the airplane's tendency to turn into the wind. In a crosswind from the right to the left, propeller forces may aggravate left-turning tendency.
As the forward speed of the airplane increases, the pilot should only apply enough aileron pressure to keep the airplane laterally aligned with the runway centerline. The pilot must maintain some aileron pressure throughout the takeoff roll to keep the crosswind from raising the upwind wing. If the upwind wing rises, the amount of wing surface exposed to the crosswind will increase, which may cause the airplane to skip — a series of very small bounces caused by the airplane attempting to fly and then settling back onto the runway. As the airplane sideways, these bounces develop into side-skipping, which imposes severe side stresses on the landing gear and may result in structural failure.
During a crosswind takeoff roll, it is important that the pilot hold sufficient aileron pressure into the wind not only to keep the upwind wing from rising but to hold that wing down so that the airplane sideslips into the wind enough to counteract drift immediately after lift-off.
As the nose-wheel raises off of the runway, the pilot should hold aileron pressure into the wind. The downwind main wheel may lift off the runway first, with the remainder of the takeoff roll being made on that one main wheel. This is acceptable and is preferable to side-skipping.
If a significant crosswind exists, the pilot should hold the main wheels on the ground slightly longer than in a normal takeoff so that a smooth but very definite lift-off can be made. This allows the airplane to leave the ground under more positive control and prevents possible damage that would result from the airplane settling back to the runway while drifting.
Crosswind Initial Climb
As takeoff acceleration occurs, the efficiency of the up-aileron will increase with aircraft speed. The yoke, which is initially turned into the wind, can be relaxed to the extent necessary to keep the aircraft aligned with the runway.
Once airborne, the upwind wing will have a tendency to be lower than the downwind wing. Rudder input will be necessary to maintain runway alignment, resulting in a sideslip.
As the aircraft establishes a climb, the sideslip should be replaced with a crab to maintain the ground track, with the nose turned into the wind to offset the crosswind. Wings are brought to level, and rudder input is adjusted to maintain runway alignment.
The force of a crosswind may vary within a few hundred feet of the ground. The pilot should check the ground track frequently and adjust the wind correction angle as necessary.
Common errors made while performing crosswind takeoffs include:
Ground Effect on Takeoff
Ground effect is a condition of improved performance encountered when the airplane is operating very close to the ground.
Ground effect can be detected and normally occurs up to an altitude equal to one wingspan above the surface.
Ground effect is most significant when the airplane maintains a constant attitude at low airspeed at low altitude. This can be during takeoff, when the airplane lifts off and accelerates to climb speed. It also can be during the landing flare before touchdown.
When the wing is under the influence of ground effect, there is a reduction in upwash, downwash, and wingtip vortices. As a result of the reduced wingtip vortices, induced drag is reduced.
When the wing is at a height equal to 25% the wingspan, the reduction in induced drag is about 25%. When the wing is at a height equal to 10% the span, the reduction in induced drag is about 50%.
The takeoff roll, lift-off, and the beginning of the initial climb are accomplished within the ground effect area.
Because of local increases in static pressure, the airspeed indicator and altimeter will indicate slightly lower values than they should. The vertical speed indicator will indicate a descent.
As the airplane lifts off and climbs out of the ground effect area, it will require an increase in angle of attack to maintain lift coefficient. Induced drag will increase. An increase in downwash at the horizontal tail will create a a pitch-up tendency. As static source pressure decreases, indicated airspeed increases.
Under conditions of high-density altitude, high temperature, and/or maximum gross weight, the airplane may be able to lift off but will be unable to climb out of ground effect. Lift off before attaining recommended flight airspeed incurs more drag, which requires more power to overcome. On a normal takeoff at full power, additional power is not available. Under marginal conditions, it is important that the airplane takes off at the speed recommended for adequate initial climb performance.
In certain circumstances, ground effect can be used to the pilot's advantage. When taking off from a rough surface, the pilot should apply as much weight to the wings as possible during the ground run and lift off, using ground effect as an aid, prior to attaining true flying speed. The pilot should reduce AOA to attain normal airspeed before attempting to fly out of the ground effect areas.
Short-Field Takeoff and Maximum Performance Climb
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. The airplane's POH/AFM always should be consulted.
Best angle of climb airspeed (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.
Taking off from a short field requires the takeoff to be started from the very beginning of the takeoff area.
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.
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.
After becoming airborne, the pilot will maintain a wings-level climb at Vx until all obstacles have been cleared. If no obstacles are present, the pilot will maintain a wings-level climb at Vx 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.
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. If the airplane becomes prematurely airborne, the initial climb will remain flat until the pilot reaches Vx, and the ability to clear obstacles becomes diminished.
Some airplanes have a natural tendency to lift off well before reaching Vx. 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 clear of the runway surface. This is preferable to forcing the airplane to remain on the ground with forward- elevator pressure until Vx is attained.
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. Raise the flaps in increments to avoid sudden loss of lift and settling of the airplane.
Common errors in the performance of short-field takeoffs and maximum performance climbs include:
Soft/Rough-Field Takeoff and Climb
Takeoffs and climbs from soft fields or rough fields require getting the airplane airborne as quickly as possible. This eliminates drag caused by tall grass, soft sand, mud, uneven surfaces, and snow. It also may require climbing over an obstacle.
The technique makes judicious use of ground effect to reduce landing gear drag. It requires an understanding of the airplane's slow-speed characteristics and responses.
Taking off from a soft surface reduces the airplane's ability to accelerate during the takeoff roll. It may prevent the airplane from reaching adequate takeoff speed.
To lift-off from a soft or rough field, the pilot should transfer the support of the airplane's weight as rapidly as possible from the wheels to the wings as the takeoff roll proceeds. This is done by establishing and maintaining a relatively high angle of attack or nose-high pitch attitude as early as possible.
If recommended by the manufacturer, the pilot should lower the wing flaps prior to starting the takeoff roll. This provides additional lift and transfers the airplane's weight from the wheels to the wings as early as possible.
When the airplane is held at a nose-high attitude throughout the takeoff run, the wings increasingly relieve the wheels of the airplane's weight as speed increases and lift develops, thereby minimizing the drag caused by surface irregularities or adhesion.
If a nose-high attitude is accurately maintained, the airplane virtually flies itself off the ground. However, because of ground effect, it will become airborne at an airspeed slower than a safe climb speed.
After the airplane becomes airborne, the pilot should gently lower the nose with the wheels clear of the surface. The airplane should accelerate to Vy, or to Vx if obstacles must be cleared.
The pilot should not attempt to climb out of ground effect before reaching the sufficient climb airspeed. It is essential that the airplane remain in ground effect until at least Vx is reached. Any attempt to climb prematurely or too steeply may cause the airplane to settle back to the surface as a result of the loss of ground effect.
In the event an obstacle must be cleared after a soft-field takeoff, the pilot should perform the climb-out at Vx until the obstacle has been cleared. The pilot should then adjust the pitch attitude to Vy and retract the gear and flaps. If departing from an airstrip with wet snow or slush on the takeoff surface, the gear should not be retracted immediately so that any wet snow or slush to be air-dried.
Common errors in the performance of soft/rough field takeoff and climbs include:
A rejected takeoff may be necessary due to a malfunctioning powerplant, inadequate acceleration, runway incursion, or air traffic conflict.
Prior to takeoff, the pilot should identify a point along the runway at which the airplane should be airborne. If that point is reached and the airplane is not airborne, immediate action should be taken to discontinue the takeoff.
Noise abatement procedures have been developed for many airports. These include standardized profiles and procedures that lower aircraft noise in residential areas. Many local communities have pressured airports into developing specific operational procedures that help limit aircraft noise while operating overhead.
Most noise-abatement information comes from the Chart Supplements, local and regional publications, printed handouts, operator bulletin boards, safety briefings, and local air traffic facilities.
Reminder signs may be installed at the taxiway hold positions for applicable runways to remind pilots to use and comply with noise abatement procedures on departure.
Commercial Pilot & Flight Instructor Test Questions
When explaining the techniques used for making short- and soft-field takeoffs, if would be correct to state that during soft-field takeoffs, lift-off should be made as soon as possible.
The indicated lift-off airspeed for short-field takeoffs in a particular aircraft will normally be greater than for soft- or rough-field takeoffs.
Immediately after takeoff, a downwind turn close to the ground is not good practice because it increases the hazards involved should an emergency landing become necessary.