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Flying
Handbook Menu > Ground
Operations > Taxiing
The following basic taxi information is applicable
to both nosewheel and tailwheel airplanes. Taxiing is the controlled
movement of the airplane under its own power while on the ground.
Since an airplane is moved under its own power between the parking
area and the runway, the pilot must thoroughly understand and
be proficient in taxi procedures. An awareness of other aircraft
that are taking off, landing, or taxiing, and consideration
for the right-ofway of others is essential to safety. When taxiing,
the pilot’s eyes should be looking outside the airplane,
to the sides, as well as the front. The pilot must be aware
of the entire area around the airplane to ensure that the airplane
will clear all obstructions and other aircraft. If at any time
there is doubt about the clearance from an object, the pilot
should stop the airplane and have someone check the clearance.
It may be necessary to have the airplane towed or physically
moved by a ground crew. It is difficult to set any rule for
a single, safe taxiing speed. What is reasonable and prudent
under some conditions may be imprudent or hazardous under others.
The primary requirements for safe taxiing are positive control,
the ability to recognize potential hazards in time to avoid
them, and the ability to stop or turn where and when desired,
without undue reliance on the brakes. Pilots should proceed
at a cautious speed on congested or busy ramps. Normally, the
speed should be at the rate where movement of the airplane is
dependent on the throttle. That is, slow enough so when the
throttle is closed, the airplane can be stopped promptly. When
yellow taxiway centerline stripes are provided, they should
be observed unless necessary to clear airplanes or obstructions.
figure2-10. Flight control positions
during taxi.
When taxiing, it is best to slow down before
attempting a turn. Sharp, high-speed turns place undesirable
side loads on the landing gear and may result in an uncontrollable
swerve or a ground loop. This swerve is most likely to occur
when turning from a downwind heading toward an upwind heading.
In moderate to high-wind conditions, pilots will note the airplane’s
tendency to weathervane, or turn into the wind when the airplane
is proceeding crosswind. When taxiing at appropriate speeds
in no-wind conditions, the aileron and elevator control surfaces
have little or no effect on directional control of the airplane.
The controls should not be considered steering devices and should
be held in a neutral position. Their proper use while taxiing
in windy conditions will be discussed later. [figure2-10] Steering
is accomplished with rudder pedals and brakes. To turn the airplane
on the ground, the pilot should apply rudder in the desired
direction of turn and use whatever power or brake that is necessary
to control the taxi speed. The rudder pedal should be held in
the direction of the turn until just short of the point where
the turn is to be stopped. Rudder pressure is then released
or opposite pressure is applied as needed. More engine power
may be required to start the airplane moving forward, or to
start a turn, than is required to keep it moving in any given
direction. When using additional power, the throttle should
immediately be retarded once the airplane begins moving, to
prevent excessive acceleration. When first beginning to taxi,
the brakes should be tested for proper operation as soon as
the airplane is put in motion. Applying power to start the airplane
moving forward slowly, then retarding the throttle and simultaneously
applying pressure smoothly to both brakes does this. If braking
action is unsatisfactory, the engine should be shut down immediately.
The presence of moderate to strong headwinds and/or a strong
propeller slipstream makes the use of the elevator necessary
to maintain control of the pitch attitude while taxiing. This
becomes apparent when considering the lifting action that may
be created on the horizontal tail surfaces by either of those
two factors. The elevator control in nosewheel-type airplanes
should be held in the neutral position, while in tailwheel-type
airplanes it should be held in the aft position to hold the
tail down. Downwind taxiing will usually require less engine
power after the initial ground roll is begun, since the wind
will be pushing the airplane forward. [figure2-11] To avoid
overheating the brakes when taxiing downwind, keep engine power
to a minimum. Rather than continuously riding the brakes to
control speed, it
is better to apply brakes only occasionally. Other than sharp
turns at low speed, the throttle should always be at idle before
the brakes are applied. It is a common student error to taxi
with a power setting that requires controlling taxi speed with
the brakes. This is the aeronautical equivalent of driving an
automobile with both the accelerator and brake pedals depressed.
When taxiing with a quartering headwind, the
wing on the upwind side will tend to be lifted by the wind unless
the aileron control is held in that direction (upwind aileron
UP). [figure2-12] Moving the aileron into the UP position reduces
the effect of the wind striking that wing, thus reducing the
lifting action. This control movement will also cause the downwind
aileron to be placed in the DOWN position, thus a small amount
of lift and drag on the downwind wing, further reducing the
tendency of the upwind wing to rise.
figure2-11. Downwind taxi.
figure2-12. Quartering headwind.
When taxiing with a quartering tailwind, the
elevator should be held in the DOWN position, and the upwind
aileron, DOWN. [figure2-13] Since the wind is striking the
airplane from behind, these control positions reduce the tendency
of the wind to get under the tail and the wing and to nose the
airplane over.
figure2-13. Quartering tailwind.
The application of these crosswind taxi corrections
helps to minimize the weathervaning tendency and ultimately
results in making the airplane easier to steer. Normally, all
turns should be started using the rudder pedal to steer the
nosewheel. To tighten the turn after full pedal deflection is
reached, the brake may be applied as needed. When stopping the
airplane, it is advisable to always stop with the nosewheel
straight ahead to relieve any side load on the nosewheel and
to make it easier to start moving ahead.
During crosswind taxiing, even the nosewheel-type
airplane has some tendency to weathervane. However, the weathervaning
tendency is less than in tailwheel-type airplanes because the
main wheels are located farther aft, and the nosewheel’s
ground friction helps to resist the tendency. [figure2-14]
The nosewheel linkage from the rudder pedals provides adequate
steering control for safe and efficient ground handling, and
normally, only rudder pressure is necessary to correct for a
crosswind.
figure2-14. Surface area most affected
by wind.
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