PERFORMANCE BY NUMBERS.

Will there be enough runway to depart? To land?

PERFORMANCE PLANNING is ail important part of any preflight routine. Private pilots must understand how the aircraft will perform at different airports, elevations, temperatures, and pressures.

Takeoff and landing distances, single-engine service ceilings, and accelerate-stop distances are all important performance calculations that must be completed to ensure the aircraft can safely complete the flight.

These calculations are still performed for the airliners on which millions of people fly yearly. Albeit slightly more modified and automated, performance calculations are completed for every flight.

Rather than calculate takeoff distances in terms of amount of runway required, a weight limit is calculated.

The runway weight limit is derived by adding passenger, cargo, and fuel weight and then compensating for temperature, pressure, wind, and runway slope. By ensuring the aircraft is below this weight limit prior to departure, you are guaranteed adequate aircraft performance for takeoff.

Included in these performance calculations are the takeoff decision speed (V1), rotation speed (VR), single-engine safety speed (V2), and flap retraction speed (V2 +15—varies by manufacturer). These are V-speeds and are used on every takeoff to help the flight crew make performance-based decisions about whether to abort a takeoff or continue.

Should a failure of some sort occur during the takeoff roll, the flight crew will analyze the failure and must make a quick decision whether to abort the takeoff and stop the aircraft on the ground, or continue the flight and take the aircraft airborne, depending on whether the airspeed is above or below V1.

Landing performance calculations also are based upon weight. The weight at landing is calculated by deducting en-route fuel burn and taxi fuel burn from takeoff weight. Distances are computed to ensure enough available runway exists to land safely. Distances are calculated to include either full or partial landing flaps, as well as penalties for not deploying thrust reversers if they’re inoperable or not used.

These performance calculations are crucial not only to private pilots flying single-engine piston aircraft, they’re also required for large turbine-powered Transport category aircraft. The methods used to calculate performance might be vastly different, but the purpose and result are the same.

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