Climbs and climbing turns are fundamental flight maneuvers that require the pilot to manage pitch attitude, airspeed, power, and coordinated flight controls. Understanding the differences between normal climbs, best rate of climb, and best angle of climb helps pilots select the appropriate climb performance for different flight conditions. Proper coordination and control are also essential when turning during a climb.
Table of Contents
Table of Contents
When an airplane enters a climb, the forces acting on it change relative to straight-and-level flight. The airplane requires sufficient thrust to overcome drag and maintain the climb. Increased lift demands can result in greater induced drag, which may cause airspeed to decrease unless additional power is available. Therefore, the rate of climb is limited by the excess power available, while the climb angle depends on the excess thrust available.
The pilot should know the engine power settings, natural-horizon pitch attitudes, and flight instrument indications that produce the following types of climb:
- Normal climb — Performed at an airspeed recommended by the airplane manufacturer. Normal climb speed is generally higher than the best rate-of-climb speed. The additional airspeed provides better engine cooling, greater control authority, and better visibility over the nose of the airplane. A normal climb is sometimes referred to as a cruise climb.
- Best rate of climb (VY) — Produces the greatest altitude gain over a given period of time. This airspeed is typically used after takeoff when maximum altitude gain per unit of time is desired, provided obstacle clearance and the airplane’s operating procedures permit its use.
- Best angle of climb (VX) — Performed at an airspeed that produces the greatest altitude gain over a given horizontal distance. The best angle of climb results in a steeper climb, although the airplane takes more time to reach the same altitude than it would at the best rate-of-climb speed. This airspeed is used to clear obstacles, such as a line of trees, after takeoff. [Figure 1]
It should be noted that, as altitude increases, the airspeed for best angle of climb generally increases while the airspeed for best rate of climb generally decreases. Performance charts contained in the Airplane Flight Manual or Pilot’s Operating Handbook (AFM/POH) should be consulted to determine the correct airspeed for the desired climb profile under the prevailing environmental conditions.
The best angle-of-climb and best rate-of-climb speeds converge at the absolute ceiling, where the airplane has no excess power available to sustain a climb. At this altitude, the maximum rate of climb is zero. [Figure 2]
Establishing a Climb
A straight climb is entered by gently increasing back pressure on the elevator flight control to establish the desired pitch attitude relative to the natural horizon while simultaneously increasing engine power to the recommended climb setting. The wingtips and natural horizon should be used as visual references while the flight instruments are cross-checked to verify performance.
In many airplanes, increasing power causes an increase in airflow over the horizontal stabilizer, which may cause the airplane’s pitch attitude to increase more than desired. The pilot should anticipate these slipstream effects, as well as changes in airspeed and lift, and apply the appropriate flight control pressures to achieve the desired pitch attitude.
If a climb is started from cruise flight, the airspeed gradually decreases as the airplane enters a stabilized climbing attitude. The thrust required to maintain straight-and-level flight at a given airspeed may not be sufficient to maintain that same airspeed in a climb. The increased drag associated with a climb results partly from the additional lift required to support the airplane while its flight path is inclined. Increased lift produces more induced drag. This is why additional power may be needed and why a sustained climb requires excess thrust.
For practical purposes, the force of gravity acting on the airplane remains essentially constant. A force-vector diagram helps explain how the forces acting on the airplane change during a climb. The lift vector acts perpendicular to the relative wind, and its direction changes as the airplane’s flight path changes. Thrust must provide the force required to overcome drag and support the climb along the flight path.
Power should be advanced to the recommended climb setting. On airplanes equipped with a controllable-pitch propeller, the propeller control may need to be adjusted before increasing engine power, in accordance with the manufacturer’s recommended procedure. Some airplanes may be equipped with cowl flaps to facilitate effective engine cooling. The cowl flaps should be positioned as recommended to keep cylinder head temperatures within the manufacturer’s specified limits.
Normally aspirated engines experience a reduction in power as altitude increases because air density decreases. The reduction in power is indicated by a decrease in revolutions per minute (rpm) in airplanes with fixed-pitch propellers and by a decrease in manifold pressure in many airplanes equipped with controllable-pitch propellers.
The pilot should monitor the engine instruments to ensure that climb power is maintained as appropriate and that engine pressures and temperatures remain within the manufacturer’s limits. As available power decreases during the climb, the pilot may need to adjust the throttle or power lever to maintain the recommended climb power setting.
The pilot should understand propeller effects during a climb and when using high power settings. In many airplanes, the propeller rotates clockwise when viewed from the pilot’s position. As pitch attitude increases, the effects of asymmetric propeller loading become more pronounced. This condition is commonly called P-factor.
P-factor results from the descending propeller blade producing more thrust than the ascending blade at a high angle of attack. In a typical clockwise-rotating propeller, the descending blade is on the right side of the propeller disc when viewed from the cockpit. This asymmetric thrust produces a yawing moment that tends to move the nose of the airplane to the left. The pilot compensates for this effect with appropriate right rudder pressure.
In addition, torque acting opposite to the direction of propeller rotation tends to roll the airplane to the left. Under these conditions, torque and P-factor can contribute to left rolling and yawing tendencies. The pilot should use coordinated rudder and aileron inputs as necessary to maintain the desired heading and wings-level attitude. During initial climb practice, these corrections may seem awkward; however, with experience, compensation for propeller effects becomes more instinctive.
As airspeed decreases while the climb is being established, the airplane’s pitch attitude may tend to decrease unless the pilot applies additional elevator back pressure. Nose-up elevator trim should be used as appropriate to relieve sustained control pressure and help maintain the desired pitch attitude.
Throughout the climb, when the recommended climb power setting is maintained, pitch attitude and elevator control are used to manage airspeed. The pilot should use the natural horizon as a visual reference for pitch attitude and cross-check the flight instruments to verify climb performance. [Figure 3]
To return to straight-and-level flight from a climb, the pilot must begin leveling off before reaching the desired altitude. Level-off should begin at approximately 10 percent of the rate of climb, expressed in feet per minute. For example, if the airplane is climbing at 500 feet per minute (fpm), leveling off should begin approximately 50 feet before reaching the desired altitude.
The pitch attitude should be reduced smoothly and gradually to allow the airspeed to increase. Reducing the pitch attitude too rapidly without allowing the airspeed to increase proportionately may result in a loss of altitude.
After the airplane is established in level flight at a constant altitude, climb power should be retained temporarily so that the airplane can accelerate to cruise airspeed. When the desired cruise airspeed is reached, the throttle and propeller control, if equipped, should be adjusted to the recommended cruise power setting, and the airplane should be retrimmed.
Climbing Turns
When performing climbing turns, the following factors should be considered:
- With a constant power setting, the same pitch attitude and airspeed may not be maintained in a bank as in a straight climb because the airplane requires additional lift to turn. The airplane may climb at a shallower angle because some of the lift is directed horizontally to produce the turn.
- Steep bank angles significantly decrease the rate of climb. The pilot should establish and maintain an appropriate bank angle throughout the turn.
- The pilot should maintain the desired airspeed and a coordinated, consistent rate of turn in both right and left turns. Coordination of all flight controls is essential.
All the factors that affect an airplane during level, constant-altitude turns also affect it during climbing turns. The pilot must manage the airplane’s inherent stability, overbanking tendencies, adverse yaw, propeller effects, reduction of the vertical component of lift, and increased drag through appropriate flight control inputs.
Climbing turns may be established by entering the climb first and then banking into the turn, or by initiating the climb and turn simultaneously. During climbing turns, as in other turns, the reduction in the vertical component of lift must be compensated for as necessary to maintain the desired climb path.
When a turn is combined with a climb, the additional drag and reduced vertical component of lift may require an increase in pitch attitude and appropriate power adjustments. When climbing and turning simultaneously, shallow bank angles are generally more effective for maintaining climb performance. Medium or steep bank angles can significantly reduce climb performance and may prevent the airplane from climbing under some conditions.
Common Errors
Common errors when performing climbs and climbing turns include:
- Attempting to establish the climbing pitch attitude primarily by referencing the airspeed indicator and chasing the airspeed.
- Applying elevator pressure too aggressively, resulting in an excessive climb angle.
- Applying inadequate or inappropriate rudder pressure during climbing turns.
- Allowing the airplane to yaw during climbs, usually because of inadequate right rudder pressure.
- Fixating on the airplane’s nose during straight climbs, resulting in a climb with one wing low.
- Initiating a climbing turn without coordinated flight control inputs, resulting in inadequate turning and a climb with one wing low.
- Improper coordination resulting in a slip that reduces climb performance and may result in little or no altitude gain.
- Failing to maintain a constant pitch attitude and bank angle during climbing turns.
- Attempting to exceed the airplane’s climb capability.
- Applying excessive forward elevator pressure during level-off, resulting in a loss of altitude or excessive negative G-forces.