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4.3.4.1.1A take-off alternate aerodrome shall be selected and specified in theoperational flight plan if either the meteorological conditions at theaerodrome of departure are below the operator's established aerodromelanding minima for that operation or if it would not be possible to return tothe aerodrome of departure for other reasons.
4.3.4.1.2The take-off alternate aerodrome shall be located within the following flighttime from the aerodrome of departure:a) for aeroplanes with two engines, one hour of flight time at a one-engineinoperativecruise speed determined from the aircraft operating manual,calculated in ISA and still-air conditions using the actual take-off mass; orb) for aeroplanes with three or more engines, two hours of flight time at anall-engine operating cruising speed, determined from the aircraft operatingmanual, calculated in ISA and still-air conditions using the actual take-offmass; orc) for aeroplanes engaged in extended diversion time operations (EDTO)where an alternate aerodrome meeting the distance criteria of a) or b) is notavailable, the first available alternate aerodrome located within the distanceof the operator?s approved maximum diversion time considering the actualtake-off mass.
4.1.4.1.3For an aerodrome to be selected as a take-off alternate the availableinformation shall indicate that, at the estimated time of use, the conditionswill be at or above the operator's established aerodrome operating minimafor that operation.
4.3.4.2 En-route alternate aerodromesEn-route alternate aerodromes, required by 4.7 for extended diversion timeoperations by aeroplanes with two turbine power-units, shall be selected andspecified in the operational and air traffic services (ATS) flight plans.