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Use of speedbrakes does not appreciably affect airplane roll response. While using
the speedbrakes in descent, allow sufficient altitude and airspeed margin to level
off smoothly. Lower the speedbrakes before adding thrust.
To avoid buffeting, use of speedbrakes with flaps greater than 5 should be avoided.
If circumstances dictate the use of speedbrakes with flaps extended, high sink
rates during the approach should be avoided. Speedbrakes should be retracted
before reaching 1,000 feet AGL.
The flaps are normally not used for increasing the descent rate. Normal descents
are made in the clean configuration to pattern or instrument approach altitude.
October 31, 2006
777/787 Flight Crew Training Manual
Climb, Cruise, Descent and
Holding
Copyright © The Boeing Company. See title page for details.
FCT 777/787 Preliminary (TM) 4.23
When descending with the autopilot engaged and the speedbrakes extended at
speeds near VMO/MMO, the airspeed may momentarily increase to above
VMO/MMO if the speedbrakes are retracted quickly. To avoid this condition,
smoothly and slowly retract the speedbrakes to allow the autopilot sufficient time
to adjust the pitch attitude to maintain the airspeed within limits.
When the speedbrakes are retracted during altitude capture near VMO/MMO, a
momentary overspeed condition may occur. This is because the autopilot captures
the selected altitude smoothly by maintaining a fixed path while the thrust is at or
near idle. To avoid this condition, it may be necessary to reduce the selected speed
and/or descent rate prior to altitude capture or reduce the selected speed and delay
speedbrake retraction until thrust is increased to maintain level off airspeed.
Flaps and Landing Gear
Normal descents are made in the clean configuration to pattern or instrument
approach altitude. If greater descent rates are desired, extend the speedbrakes.
When thrust requirements for anti-icing result in less than normal descent rates
with speedbrakes extended, or if higher than normal descent rates are required by
ATC clearance, the landing gear can be lowered to increase the rate of descent.
Extend the flaps when in the terminal area and conditions require a reduction in
airspeed below flaps up maneuvering speed. Normally select flaps 5 prior to the
approach fix going outbound, or just before entering downwind on a visual
approach.
Note: Avoid using the landing gear for increased drag above 200 knots. This
minimizes passenger discomfort and increases gear door life.
Speed Restrictions
Speed restrictions below specific altitudes/flight levels and in the vicinity of
airports are common. At high gross weights, minimum maneuvering speed may
exceed these limits. Consider extending the flaps to attain a lower maneuvering
speed or obtain clearance for a higher airspeed from ATC.
Other speeds may be assigned by ATC. Pilots complying with speed adjustments
are expected to maintain the speed within plus or minus 10 knots.
Engine Icing During Descent
The use of anti-ice and the increased thrust required increases the descent
distance. Therefore, proper descent planning is necessary to arrive at the initial
approach fix at the correct altitude, speed, and configuration. The anticipated
anti-ice use altitude should be entered on the DESCENT FORECAST page to
assist the FMC in computing a more accurate descent profile.
October 31, 2006
777/787 Flight Crew Training Manual
Climb, Cruise, Descent and
Holding
Copyright © The Boeing Company. See title page for details.
4.24 FCT 777/787 Preliminary (TM)
Engine icing may form when not expected and may occur when there is no
evidence of icing on the windshield or other parts of the airplane. Once ice starts
to form, accumulation can build very rapidly. Although one bank of clouds may
not cause icing, another bank, which is similar, may induce icing.
Note: The engine anti-icing system should be AUTO or ON whenever icing
conditions exist or are anticipated. Failure to follow the recommended
anti-ice procedures can result in engine stall, overtemperature or engine
damage.
Holding
Start reducing to holding airspeed 3 minutes before arrival time at the holding fix
so that the airplane crosses the fix, initially, at or below the maximum holding
airspeed.
777-200 - 777-300ER
If the FMC holding speed is greater than the ICAO or FAA maximum holding
speed, holding may be conducted at flaps 1, using flaps 1 maneuvering speed.
Flaps 1 uses approximately 7% more fuel than flaps up. Holding speeds in the
FMC provide an optimum holding speed based upon fuel burn and speed
capability, but are never lower than flaps up maneuvering speed.
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787机组训练手册Flight Crew Training Manual 787(60)
