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. This minimizes passenger discomfort and increases gear door life.
Copyright . The Boeing Company. See title page for details.
October 31, 2006 FCT 737 (TM) 4.21
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
737-300 - 737-500 Since all engines have been manufactured or modified to use a single idle speed in flight, the use of TAI does not increase thrust as it does in other models.
.
U5.0 and later FMCs use single idle speed logic to compute the descent
profile. TAI entries on the DESCENT FORECAST page have no effect on
the descent profile
.
U4.0 and earlier FMCs were developed before the engine modification for
full time high idle was incorporated. On these early FMCs, single idle
speed logic, using low idle speed, is used to compute the descent profile,
except for those altitudes where anti-ice use is entered on the DESCENT
FORECAST page. Since actual idle thrust is higher than the FMC uses in
planning, the FMC constructs a steeper descent profile than will be
achieved by the airplane. The result is that the airplane pitches down to
capture and maintain the path and the airspeed increases. To assist the
FMC in computing a more accurate descent profile, anti-ice use may be
entered on the DESCENT FORECAST page for the entire descent.
737-600 - 737-900 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.
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 turned 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.
Copyright . The Boeing Company. See title page for details.
4.22 FCT 737 (TM) October 31, 2006
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.
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 10% 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.
Maintain clean configuration if holding in icing conditions or in turbulence. If the holding pattern has not been programmed in the FMC, the initial outbound leg should be flown for 1 minute or 1 1/2 minutes as required by altitude. Timing
for subsequent outbound legs should be adjusted as necessary to achieve proper inbound leg timing. In extreme wind conditions or at high holding speeds, the defined holding pattern
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