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An improper rotation can have an effect on the command speed after liftoff. If the
rotation is delayed beyond V2 + 15, the speed commanded by the flight director
is rotation speed up to a maximum of V2 + 25. An earlier liftoff does not affect the
commanded initial climb speed, however, either case degrades overall takeoff
performance.
The following diagram shows how a slow or under rotation during takeoff
increases the distance to a height of 35 feet compared to a normal rotation.
Slow or Under Rotation (Typical)
V R
V R
V R Liftoff 35'
Liftoff
Liftoff
35'
35'
Normal rotation
(1° per sec slower than normal) Up to 1000’
Slow rotation
Under rotation
(Rotate to 5° less than target) Up to 250’
October 31, 2004
767 Flight Crew Training Manual
Takeoff and Initial Climb
Copyright © The Boeing Company. See title page for details.
3.10 FCT 767 (TM)
Center-Of-Gravity (C.G.) Effects
When taking off at light weight and with an aft C.G., the combination of full thrust,
rapid thrust application, and sudden brake release may tend to pitch the nose up,
reducing nosewheel steering effectiveness. With C.G. at or near the aft limit,
maintain forward pressure on the control column until 80 knots to increase
nosewheel steering effectiveness. Above 80 knots, relax the forward control
column pressure to the neutral position. At light weight and aft C.G., use of
reduced thrust and rolling takeoff technique is recommended whenever possible.
The rudder becomes effective between 40 and 60 knots.
Operation with Alternate Forward Center of Gravity Limit for Takeoff
Takeoff performance is based on the forward CG limitations as defined in the
AFM. However, takeoff performance can be improved by taking credit for an
alternate (further aft) forward CG limit if shown in the AFM. Use of this data
provides higher performance-limited takeoff weights than the basic AFM
performance data.
Typically alternate forward CG is used to increase performance-limited takeoff
weight for field length, climb or obstacle limited departures. Another potential
benefit of alternate forward CG is to allow greater thrust reduction which
increases engine reliability and reduces engine maintenance costs. However, this
improved performance capability is only available if the airline has the certified
data in their AFM and has approval from their regulatory agency to operate the
airplane at an alternate forward CG limit.
A more aft CG increases the lift available at a given angle of attack due to the
reduction in nose up trim required from the horizontal stabilizer. This allows VR
and V2 to be reduced, which in turn reduces the field length required for takeoff.
Reduction in field length required can also permit an increased field length limited
weight. In most instances this reduction in nose up trim also results in a decrease
in drag which improves the airplane’s climb capability.
Note: The FMC calculated takeoff speeds and QRH takeoff speeds are not valid
for operations using alternate forward CG. Takeoff speeds must be
calculated using alternate forward CG performance data normally
provided by dispatch or flight operations.
October 31, 2004
767 Flight Crew Training Manual
Takeoff and Initial Climb
Copyright © The Boeing Company. See title page for details.
FCT 767 (TM) 3.11
Crosswind Takeoff
The crosswind guidelines shown below were derived through flight test data and
engineering analysis.
Note: Engine surge can occur with a strong crosswind component if takeoff
thrust is set prior to brake release. Therefore, the rolling takeoff procedure
is strongly advised when crosswind exceeds 20 knots.
Takeoff Crosswind Guidelines
Crosswind guidelines are not considered limitations. Crosswind guidelines are
provided to assist operators in establishing their own crosswind policies.
Takeoff crosswind guidelines are based upon the most adverse airplane loading
(light weight and aft center of gravity) and assume an engine out RTO. On slippery
runways, crosswind guidelines are a function of runway surface condition, and
assume proper pilot technique.
*Winds measured at 33 feet (10 m) tower height and apply for runway 148 feet
(45m) or greater in width.
** Takeoff on untreated ice or snow should only be attempted when no melting is
present.
Runway Condition Crosswind – Knots*
Dry 40
Wet 25
Standing Water/Slush 15
Snow - No Melting ** 20
Ice - No Melting ** 15
October 31, 2004
767 Flight Crew Training Manual
Takeoff and Initial Climb
Copyright © The Boeing Company. See title page for details.
　
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