Align the airplane with the runway centerline and ensure that the nosewheel is straight before applying power for takeoff. Under severe icing conditions, takeoff should be preceded by a static run-up to as high a thrust level as practical with observation of EPR and EGT to assure normal engine operation. On slippery surfaces, ensure the parking brakes are released prior to setting takeoff power to preclude a takeoff with the parking brakes set.
With a contaminated runway, a static takeoff should be performed. Advance throttles to 1.4 EPR or 80% N2 and check that EPR’s are approximately matched. If the airplane starts to move due to poor braking conditions, release the brakes and proceed with a rolling takeoff. Check all engine instruments for proper indications during the early part of this step, including the MINIMUM N1 FOR TAKEOFF, found in Section 5 or the QRH.
If the PT2 probe is blocked by a contaminate such as ice and the engine anti-ice system is off, the EPR gauge will indicate a higher thrust than the engine is actually developing. If the PT2 probe is blocked and the engine anti-ice system is on, (i.e., ice in probe, but insufficient time for anti-ice bleed air to melt the ice), the EPR gauge will indicate a lower thrust than the engine is actually developing.
Asymmetrical thrust can adversely affect directional control on slippery runways. Throttle at partial power may not assure alignment at takeoff power as engine pairs may have different spool-up rates.
On slippery runways, apply some nose down elevator to improve nosewheel traction and directional control until rudder control becomes effective for steering the airplane. Excessive forward control column pressure should be avoided and, as speed increases, the forward pressure on the control column should be reduced to lessen the possibility of nosewheel spray being ingested into the engines when operating on wet, or slush and snow-covered runways.
To maintain the heading during takeoff roll, recognize initial heading deflections early and correct by small rudder pedal steering inputs. Do not use differential thrust.
With the increased stopping distances encountered under contaminated runway conditions, consideration should be given to limiting the decision to abort at speeds between V1 -20 and V1 to engine failure, or conditions where the airplane is considered unflyable.
Difficulty with directional control may be encountered after a takeoff rejection, especially under crosswind conditions. When rejecting, ensure spoiler deployment, apply moderate forward pressure on the control column, and maintain directional control with rudder pedal steering, simultaneously applying maximum braking. Both nose wheel steering and differential braking effectiveness are reduced during wet/slippery runway operation. Do not apply excessive forward control column pressure as this will reduce the weight on the main wheels resulting in reduced braking friction. While the use of reverse thrust on wet runways is recommended to reduce the stopping distance, its prolonged use further reduces the total directional control capability (rudder blanking) as the airplane slows. Consequently, reverse thrust should be applied gradually and symmetrically (both engines operating) commensurate with the ability to maintain directional control under the existing conditions. Should directional control become a problem while in reverse thrust, reduce reverse thrust to reverse idle (or forward idle thrust, if required), regain directional control, and reapply reverse thrust as necessary. Do not attempt to maintain directional control by using asymmetric reverse thrust.
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本文链接地址：MD-80 Flight Manual 麦道80飞行手册 2(57)
