737 MAX Flight Crew Operations Manual
Supplementary Procedures -
Adverse Weather
MN-FLT-OH-201
SP.16.11
Thrust ........... Reduce as needed for flight conditions
PF
Wait 15 seconds. This allows engine vibration level to stabilize.
If engine vibration is less than 4.0 units after thrust is reduced, repeat the
above steps at approximately 15 minute intervals or sooner as needed.
Autothrottle (if needed) ..................................Engage
PF
If engine vibration is 4.0 units or greater after thrust is reduced, do the
Engine High Vibration non-normal checklist.
Wing Anti-ice Operation - In Flight
Ice accumulation on the flight deck window frames, windshield center
post, or on the windshield wiper arm may be used as an indication of
structural icing conditions and the need to turn on wing anti-ice.
In flight, the wing anti-ice system may be used as a de-icer or as an
anti-icer. The primary method is to use it as a de-icer by allowing ice to
accumulate before turning wing anti-ice on. This procedure provides the
cleanest airfoil surface, the least possible runback ice formation, and the
least thrust and fuel penalty. Normally it is not necessary to shed ice
periodically unless extended flight through icing conditions is necessary
(holding).
The secondary method is to use wing anti-ice before ice accumulation.
Operate the wing anti-ice system as an anti-icer only during extended
operations in moderate or severe icing conditions, such as holding.
CAUTION: Do not use wing anti-ice when TAT is above 10°C.
CAUTION: Use of wing anti-ice above approximately FL350 may
cause bleed trip off and possible loss of cabin
pressure.
Note:
Prolonged operation in icing conditions with the leading edge
and trailing edge flaps extended is not recommended. Holding
in icing conditions with flaps extended is prohibited.
When wing anti-ice is needed:
WING ANTI-ICE switch ..................................... ON
PM
Verify that the L and R VALVE OPEN lights illuminate
bright, then dim.
When wing anti-ice is no longer needed:
WING ANTI-ICE switch ................................... OFF
PM
March 1, 2021