WARNING: If windshear is encountered at or above the actual gross weight VR, do not attempt to accelerate to the increased VR, but rotate without hesitation. If windshear is encountered at or near the actual gross weight VR and airspeed suddenly decreases, there may not be sufficient runway left to accelerate back to normal VR. If there is insufficient runway left to stop, initiate a normal rotation at least 2,000 feet before the end of the runway, even if airspeed is low. Higher than normal attitudes may be required to lift off in the remaining runway. Aft body contact may occur.
Throttles may be advanced to the mechanical stops. If increased airspeed was not used prior to liftoff, accelerating to higher than normal airspeed after liftoff is not recommended. Reducing pitch attitude at low altitude to accelerate might produce a hazard if windshear is encountered.
Once the takeoff is initiated, the flight crew should be alert for airspeed fluctuations. If significant airspeed variations occur below V1, the takeoff should be aborted if sufficient runway remains.
Caution: Accelerate/Stop distances are computed assuming a normal acceleration to V1. Airspeed fluctuations may cause the aircraft to achieve V1 at a point farther down the runway than anticipated. Therefore, the aircraft may not be able to stop on the runway.
Approach Precautions
Due to configuration and power settings, aircraft are the most vulnerable to windshear effects during the approach and landing phase of flight. Airspeed losses and excessive sink rates should be immediately responded to by the flight crew since the aircraft may not be able to recover from a situation that has been allowed to progress unchecked. A stabilized approach should be established no later than 1,000 feet AGL to improve windshear recognition capability.
Select minimum normal landing flap consistent with the field length, and do not use autothrottles.
The target airspeed bug should be set based on the surface winds in the usual manner. During the approach, the pilots should continuously monitor airspeed loss reports from other aircraft ahead or the tower if equipped with Terminal Doppler Weather Radar. The reported airspeed loss should be added to VREF and if this value is in excess of target airspeed, the pilot should increase to and maintain this speed. (The target bug should remain set based on the surface wind additive only.) If the reported airspeed loss, when added to VREF results in a speed less than target airspeed, maintain target airspeed. If the additive to VREF (due to either surface wind or reported loss) results in an adjustment in excess of VREF + 20 knots, the approach should not be continued.
Airspeed additive due to reported airspeed loss should be maintained to touchdown; however, the aircraft should not be allowed to float beyond the touchdown zone.
WARNING: Increased touchdown speeds increase stopping distance. An additional 20 knots at touchdown can increase stopping distance by as much as 25%.
Vertical speed should be closely monitored. If the descent rate required to maintain the glide path is significantly different than expected (based on groundspeed and descent slope), continuance of the approach may not be a safe course of action.
Caution: At airports equipped with Terminal Doppler Weather Radar, a missed approach should be executed if the Microburst Alert or a Windshear Alert accompanied by a reported airspeed loss of greater than 20 knots, is received.
As increase in airspeed and ballooning above the glideslope may be first indications of a windshear. Do not make large thrust reductions. This increase in performance may be followed soon by a rapid airspeed loss and an additional loss of performance due to a downdraft. The pilot may choose to accept this initial airspeed gain anticipating an equal or greater loss. In windshear conditions, a flight director and/or autoflight system which does not have windshear recovery enhancements may command a pitch attitude change to follow target airspeeds or a fixed pitch attitude regardless of flight path degradation. This guidance may be in conflict with the proper procedures for windshear recovery and must be disregarded. Such systems must be disconnected, turned off, or disregarded if recovery is required. Do not follow TOGA commands.
Recovery Maneuver
The following actions are recommended whenever flight path control becomes marginal below 1000 feet AGL on takeoff or approach. As guidelines, marginal flight path control may be indicated by deviations from target conditions in excess of:
. + 15 knots indicated airspeed . + 500 FPM vertical speed deviation from normal . + 5 degrees pitch attitude change . + 1 dot glideslope displacement
. Unusual throttle position for a significant period of time
Exact parameters cannot be established. In certain situations where significant rates of change occur, it may be necessary to go-around before any of the above are exceeded. The determination to begin the recovery procedure is subjective and based on the pilot’s judgment of the situation.
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本文链接地址：MD-80 Flight Manual 麦道80飞行手册 2(44)
