787 Flight Crew Operations Manual
DO NOT USE FOR FLIGHT
Supplementary Procedures -
Adverse Weather
Copyright © The Boeing Company. See title page for details.
D615Z003-TBC SP.16.17
Climb, Cruise, and Descent Considerations
After takeoff, and when established in a clean climb configuration, use of
the autoflight system is recommended for flight through turbulence.
During climb and descent, use of VNAV or flight level change may result
in excessive pitch changes as the AFDS attempts to fly speed with the
elevators. Therefore, vertical speed mode (speed on autothrottles) is
recommended for climb and descent in severe turbulence.
During cruise, VNAV and altitude hold modes both fly speed on
autothrottles and can be used in turbulence.
[Option – RR engines]
In severe turbulence during cruise, it may be necessary to disconnect the
autothrottles to prevent excessive thrust changes. Thrust setting guidance
is available on EICAS when VNAV is engaged. Set TPR at or slightly
above the magenta VNAV target TPR indication. Change thrust setting
only if required to modify an unacceptable speed trend.
[Option – GE engines]
In severe turbulence during cruise, it may be necessary to disconnect the
autothrottles to prevent excessive thrust changes. Thrust setting guidance
is available on EICAS when VNAV is engaged. Set N1 at or slightly above
the magenta VNAV target N1 indication. Change thrust setting only if
required to modify an unacceptable speed trend.
Manual Flight in Severe Turbulence
If manual flight in severe turbulence becomes necessary, trim the airplane
for the turbulent air penetration speed. Control the airplane pitch attitude
with the elevators using the attitude indicator as the primary instrument. In
extreme drafts, large altitude changes may occur. Do not make sudden
large control inputs. Corrective actions to regain the desired attitude
should be smooth and deliberate. Altitude variations are likely in severe
turbulence and should be allowed to occur if terrain clearance is adequate.
Control airplane attitude first, then make corrections for airspeed, altitude,
and heading.
February 13, 2009
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