Types of Climb

Aircraft Climb Performance

Most aircraft accidents occur during the take-off and landing phase of the flight. Collisions with obstacles during climb out, runway overruns on landing occur every now and then. On this part of the site we will take a look at the various factors contributing to the performance of the aircraft in this part of the flight. Hopefully we help the pilot ensuring safe operation during these phases of the flight as the rules require that of the pilot in command.

There are a number of speeds defined for the aircraft where it has a certain performance. These are: best rate of climb speed and best angle of climb speed. Both are used by the pilot to reach an altitude in the minimum amount of time or distance traveled.

The climb performance of an aircraft is influenced by factors as: amount of applied power, airspeed, drag in the form of flaps or landing gear and weight. We examine these factors to show the effect they have.

Climb performance

This can be measured as the climb angle (V_X) or the rate of climb (V_Y) and certain factors will influence these, although these speeds will remain more or less the same, the result (climb rate or angle) will change.

Power and Speed

The amount of power used during the climb over the power required directly results in a different climb performance. If your aircraft is not climbing as expected, check if full power (or recommended climb power) is set.

Flying with a higher or lower airspeed (than used for best climb angle or rate) will result in a lower climb performance compared to the optimum speeds.

Weight

A heavier aircraft decreases the climb performance as the power required to maintain a given speed in level flight increases with all up weight. There is less excess power available to climb. So climb performance and service ceiling suffer.

Flaps and landing gear

Extending the flaps will decrease the climb performance as L/D ratio is less and the power required increased. The best rate-of-climb and angle-of-climb is always reached with flaps up. Hence the need to retract flaps after a go-around if obstacles are in the climb out path. Some aircraft are not able to climb if full flaps are selected due to the amount of drag involved.

Some aircraft manufacturers recommend a take-off setting for flaps during a short field or high performance take-off. Although L/D ratio will suffer and drag is increased by the flaps it will permit the aircraft to fly off the runway sooner, but the climb out performance will be less.

Just remember to not to prolong the climb at the maximum angle of climb speed as this speed is relatively low, engine cooling is poor and overheating and detonation could result. Lower the nose and increase the airspeed as soon as possible after clearing the obstacles to enhance cooling and forward view. Reduce airspeed to cruise climb speeds.

Aircraft with retractable gear should retract as soon as no more usable runway is available and a positive rate of climb is established. The drag caused by the gear reduces climb performance. Aircraft with a fixed gear have no choice in retracting but to have the gear as much as streamlined by fairings as possible.

Air density

Consist of temperature and altitude and influenced by ambient air pressure. Any change in one of these factors influences the density altitude and climb performance of any aircraft.

Altitude

An increase in altitude reduces air density and a decrease in engine power and wing and propeller (airframe) performance. Power available reduces with altitude, unless the engine is turbo- or supercharged. Power required goes up with altitude and at one point these two will be the same. The aircraft then has reached its absolute altitude. More practical is the service ceiling where the aircraft vertical speed is reduced to 100 ft/min.

Temperature and QNH

Has a direct effect on air density and thus climb performance. At any altitude where OAT is higher than standard ISA temperature climb performance will be reduced. If QNH is lower than ISA then aircraft climb performance is affected too.

Turbulence and maneuvering

Any change in the aircraft attitude due to maneuvering, turbulence and turning reduces the climb performance somewhat as part of the excess power is needed to compensate for the maneuvers.

Wind

Setting exactly the same power settings and climb speeds, with a headwind the result will be that the distance traveled over the ground is reduced whereas with a tailwind the distance over the ground is increased.
So climbing into the wind has an advantage if obstacles are in the climb out path.