737 MAX Flight Crew Operations Manual
Supplementary Procedures -
Adverse Weather
MN-FLT-OH-201
SP.16.27
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:
Takeoff
• Takeoff with full rated takeoff thrust is recommended, unless the use
of a fixed derate is required to meet a dispatch performance
requirement
• For optimum takeoff performance, use flaps 5, 10 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. Rotate at the
adjusted (higher) rotation speed. This increased rotation speed
results in an increased stall margin and meets takeoff performance
requirements. 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
March 1, 2021