Flight Training - September 2013 - 48

CAREER PILOT»

TECH TALK

PERFORMANCE BY NUMBERS

Will there be enough runway to depart? To land?
» By Jared Dirkmaat

PERFORMANCE PLANNING

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A DIVISION OF THE
AOPA FOUNDATION

is an 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 performancebased 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

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FLIGHTTRAINING.AOPA.ORG

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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Flight Training - September 2013

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