Initiating Takeoff Roll
Autothrottle and flight director use is recommended for all takeoffs. However, do not follow F/D commands until after liftoff.
Note: If a possibility exists of a windshear being encountered on takeoff, flight
directors should be turned off for airplanes not equipped with a windshear
warning system.
A rolling takeoff procedure is recommended for setting takeoff thrust. It expedites takeoff and reduces risk of foreign object damage or engine surge/stall due to a tailwind or crosswind. Flight test and analysis prove that the change in takeoff roll distance due to the rolling takeoff procedure is negligible when compared to a standing takeoff.
Rolling takeoffs are accomplished in two ways:
.
if cleared for takeoff prior to or while entering the runway, maintain
normal taxi speed. When the airplane is aligned with the runway
centerline ensure the nose wheel steering tiller is released and apply
takeoff thrust by advancing the thrust levers to approximately 1.1 EPR.
Allow the engines to stabilize momentarily then promptly advance the
thrust levers to takeoff thrust (autothrottle EPR or THR). There is no need
to stop the airplane prior to adding thrust.
.
if holding in position on the runway, ensure the nose wheel steering tiller
is released, release brakes, then apply takeoff thrust as described above.
Note: Brakes are not normally held with thrust above idle unless a static run-up is required in icing conditions.
A standing takeoff procedure may be accomplished by holding the brakes until the engines are stabilized, ensure the nose wheel steering tiller is released, then release the brakes and promptly advance the thrust levers to takeoff thrust (autothrottle EPR or THR).
Allowing the engines to stabilize provides uniform engine acceleration to takeoff thrust and minimizes directional control problems. This is particularly important if crosswinds exist or the runway surface is slippery. The exact initial setting is not as important as setting symmetrical thrust.
Note: During tailwind conditions, slight EPR fluctuations may occur on some engines prior to 5 knots forward airspeed.
Note: Allowing the engines to stabilize for more than approximately 2 seconds
prior to advancing thrust levers to takeoff thrust may adversely affect
takeoff distance.
If thrust is to be set manually, smoothly advance thrust levers toward takeoff thrust. Final thrust adjustments should be made, with reference to the digital readouts, by 80 knots.
During takeoff, if an engine exceedance occurs after thrust is set and the decision is made to continue the takeoff, do not retard the thrust lever in an attempt to control the exceedance. Retarding the thrust levers after thrust is set invalidates takeoff performance. When the PF judges that altitude (minimum 400 feet AGL) and airspeed are acceptable, the thrust lever should be retarded until the exceedance is within limits and the appropriate NNC accomplished.
Use of the nose wheel steering tiller is not recommended above 30 knots. However, pilots must use caution when using the nose wheel steering tiller above 20 knots to avoid over-controlling the nose wheels resulting in possible loss of directional control. Limited circumstances such as inoperative rudder pedal steering may require the use of the nose wheel steering tiller at low speeds during takeoff and landing when the rudder is not effective. Reference the airplane Dispatch Deviations Guide (DDG) for more information concerning operation with rudder pedal steering inoperative.
Light forward pressure is held on the control column. Keep the airplane on centerline with rudder pedal steering and rudder. The rudder becomes effective between 40 and 60 knots. Maximum nose wheel steering effectiveness is available when above taxi speeds by using rudder pedal steering.
Regardless of which pilot is making the takeoff, the captain should keep one hand on the thrust levers until V1 in order to respond quickly to a rejected takeoff condition. After V1, the captain’s hand should be removed from the thrust levers.
The pilot not flying should monitor engine instruments and both primary and standby airspeed indications during the takeoff roll and announce any abnormalities. The pilot not flying should announce passing 80 knots and the pilot flying should verify that his airspeed indicator is in agreement. The pilot not flying should verify that takeoff thrust has been set and the throttle hold mode (THR HOLD) is engaged.
中國航空網 m.k6050.com
航空翻譯 www.aviation.cn
本文鏈接地址：757 Flight Crew Training Manual 機組訓練手冊(25)
