Supplementary Procedures -Adverse Weather 737 Operations Manual
If heavy rain is encountered:
ENGINE START switches .......................................................CONT Thrust Levers................................................................Adjust Slowly If thrust changes are necessary, move the thrust levers slowly. Avoid changing thrust lever direction until engines have stabilized at a selected setting.
Turbulence
During flight in light to moderate turbulence, the autopilot and/or autothrottle may remain engaged unless performance is objectionable. Increased thrust lever activity can be expected when encountering wind, temperature changes and large pressure changes. Short–time airspeed excursions of 10 to 15 knots can be expected.
Passenger signs ...................................................................................ON Passengers must be advised to fasten seat belts prior to entering areas of forecast or suspected turbulence. Instruct flight attendants to check that all passengers' seat belts are fastened.
Severe Turbulence
Autothrottle........................................................................DISENGAGE
AUTOPILOT ................................................................................... CWS A/P status annunciators display CWS for pitch and roll.
Note: If sustained trimming occurs, disengage the autopilot.
ENGINE START switches ................................................................FLT
Thrust ...................................................................................................Set Set thrust as required for the phase of flight. Change thrust setting only if required to modify an unacceptable speed trend.
Supplementary Procedures -Adverse Weather
PHASE OF FLIGHT AIRSPEED
CLIMB 280 KIAS or .73 Mach
CRUISE Use FMC recommended thrust settings. If the FMC is inoperative, refer to Performance–Inflight section for approximate N1 settings that maintain near optimum penetration airspeed.
DESCENT .73 Mach/280/250 KIAS. If severe turbulence is encountered at altitudes below 15,000 feet and the airplane gross weight is less than the maximum landing weight, the airplane may be slowed to 250 knots in the clean configuration.
Note: If an approach must be made into an area of severe turbulence, delay flap extension as long as possible. The airplane can withstand higher gust loads in the clean configuration.
Windshear
Windshear is a change of wind speed and/or direction over a short distance along the flight path. Indications of windshear are listed in the Windshear Non-Normal maneuver in this manual.
Avoidance
The flight crew should search for any clues to the presence of windshear along the intended flight path. Presence of windshear may be indicated by:
.
Thunderstorm activity
.
Virga (rain that evaporates before reaching the ground)
.
Pilot reports
.
Low level windshear alerting system (LLWAS) warnings Stay clear of thunderstorm cells and heavy precipitation and areas of
known windshear. If the presence of windshear is confirmed, delay takeoff or do not continue an approach.
Precautions
If windshear is suspected, be especially alert to any of the danger signals and be prepared for the possibility of an inadvertent encounter. The following precautionary actions are recommended if windshear is suspected:
Copyright . The Boeing Company. See title page for details.
SP.16.14 June 4, 2004
Supplementary Procedures -Adverse Weather 737 Operations Manual
Takeoff
.
Use maximum takeoff thrust instead of reduced thrust
.
For optimum takeoff performance, use flaps 5 or 15 unless limited by obstacle clearance and/or climb gradient
.
Use the longest suitable runway provided it is clear of areas of
known windshear
.
Consider increasing Vr speed to the performance limited gross weight rotation speed, not to exceed actual gross weight Vr + 20 knots. Set V speeds for the actual gross weight and use the adjusted (higher) rotation speed. If windshear is encountered at or beyond the actual gross weight Vr, do not attempt to accelerate to the increased Vr, but rotate without hesitation
.
Be alert for any airspeed fluctuations during takeoff and initial climb. Such fluctuations may be the first indication of windshear
.
Know the all–engine initial climb pitch attitude. Rotate at the
normal rate to this attitude for all non–engine failure takeoffs.
Minimize reductions from the initial climb pitch attitude until
terrain and obstruction clearance is assured, unless stick shaker
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