Improved Climb Performance Takeoff
When not field length limited, an increased climb limit weight is achieved by using the excess field length to accelerate to higher takeoff and climb speeds. This improves the climb gradient, thereby raising the climb limit weight. V1, VR and V2 are increased to maintain consistent performance relationships. V1, VR and V2 must be obtained from dispatch or the airport analysis.
Low Visibility Takeoff
Low visibility takeoff operations, below landing minima, may require a takeoff alternate. When selecting a takeoff alternate, consideration should be given to unexpected events such as an engine failure or other non-normal situation that could affect landing minima at the takeoff alternate. Operators, who have authorization for engine inoperative Category II/III operations, may be authorized lower alternate minima.
With proper crew training and appropriate runway lighting, takeoffs with visibility as low as 500ft/150m RVR may be authorized (FAA). With takeoff guidance systems and centerline lighting that meets FAA or ICAO criteria for Category III operations, takeoffs with visibility as low as 300ft/75m RVR may be authorized. Regulatory agencies may impose takeoff crosswind limits specifically for low visibility takeoffs.
All RVR readings must be equal to or greater than required takeoff minima. If the touchdown or rollout RVR system is inoperative, the mid RVR may be substituted for the inoperative system. When the touchdown zone RVR is inoperative, pilot estimation of RVR may be authorized by regulatory agencies.
Adverse Runway Conditions
Slush, standing water, or deep snow reduces the airplane takeoff performance
because of increased rolling resistance and the reduction in tire-to-ground friction. Most operators specify weight reductions to the AFM field length and or obstacle limited takeoff weight based upon the depth of powdery snow, slush, wet snow or standing water and a maximum depth where the takeoff should not be attempted.
Slush or standing water may cause damage to the airplane. The recommended maximum runway depth for slush, standing water, or wet snow is 0.5 inch (12.7 mm). For dry snow the maximum depth is 4 inches (102 mm).
A slippery runway (wet, compact snow, ice) also increases stopping distance during a rejected takeoff. Takeoff performance and critical takeoff data are adjusted to fit the existing conditions. If there is an element of uncertainty concerning the safety of an operation with adverse runway conditions, do not takeoff until the element of uncertainty is removed.
Note: Check the airport analysis or the PI section of the QRH for performance degradation for takeoff with adverse runway conditions.
During wet runway or slippery conditions, the PNF must give special attention to assuring that the thrust on the engines advances symmetrically. Any tendency to deviate from the runway centerline must immediately be countered with steering action and, if required, slight differential thrust.
Forward pressure on the control column during the initial portion of the takeoff roll (below approximately 80 knots) increases nose wheel steering effectiveness.
During takeoffs on icy runways, lag in rudder pedal steering and possible nose wheel skidding must be anticipated. Keep the airplane on the centerline with rudder pedal steering and rudder. The rudder becomes effective between 40 - 60 knots. If deviations from the centerline cannot be controlled either during the start of the takeoff roll or until the rudder becomes effective, immediately reject the takeoff.
Effect of Deicing/Anti-Icing Fluids on Takeoff
Testing of undiluted Type II and Type IV fluids has shown that some of the fluid remains on the wing during takeoff rotation and during initial climb out. The residual fluid causes a temporary decrease in lift and increase in drag. These effects are more significant at lower ambient temperatures where the fluid tends to stay on the wing longer. Operators must comply with the lowest operational use temperatures provided by the fluid manufacturer to ensure a relatively clean wing.
No performance adjustments are required for the application of deicing/anti-icing fluids. Takeoff operations with reduced thrust based on derates and/or the assumed temperature method are permitted. Use normal rotation rates.
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