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One engine inoperative landing capability shall be attainable at the alternate.
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Deck availability shall be guaranteed. The dimensions, configuration and obstacle clearance of individual helidecks or other sites shall be assessed in order to establish operational suitability for use as an alternate by each helicopter type proposed to be used.
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Weather minima shall be established taking accuracy and reliability of meteorological informa-tion into account.
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The helicopter Minimum Equipment List shall reflect essential requirements for this type of operation.
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An offshore alternate shall not be selected unless the operator has published a procedure in the Operations Manual approved or accepted by the regulatory Authority.
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When operating offshore, any spare payload capacity should be used to carry additional fuel if
it would facilitate the use of an onshore alternate. The offshore landing environment of a helideck that is proposed for use as an Offshore Alternate should be pre-surveyed and, as well as the physical characteristics, the effect of the wind direction and strength, and turbulence established. This information, which should be available to the air-craft captain at the planning stage and in flight, should be published in an appropriate form in the Operations Manual (including the orientation of the helideck) such that the suitability of the helideck for use as an offshore alternate can be assessed. The alternate helideck should meet the criteria for size and obstacle clearance appropriate to the performance requirements of the type of helicopter concerned.
The use of an offshore alternate is restricted to helicopters that can achieve one engine inoperative (OEI) in ground effect (IGE) hover at an appropriate power rating at the offshore alternate. Where the surface of the offshore alternate helideck, or prevailing conditions (especially wind velocity), precludes an OEI in ground effect (IGE) hover, OEI out of ground effect (OGE) hover perform-ance at an appropriate power rating should be used to compute the landing mass/gross weight. The landing mass/gross weight should be calculated from graphs provided in the relevant part of the Aircraft Flight Manual. When arriving at this landing mass, due account should be taken of helicop-ter configuration, environmental conditions and the operation of systems that have an adverse effect on performance. The planned landing mass of the helicopter including crew, passengers, baggage, cargo plus 30 minutes of Final Reserve fuel, should not exceed the OEI landing mass at the time of approach to the offshore alternate.
When the use of an offshore alternate is planned, an operator should not select a helideck as a desti-nation or offshore alternate unless:
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The aerodrome forecast indicates that, during a period commencing one hour after the expected arrival at the destination and offshore alternate the weather conditions will be at or above the following planning minima:
cloud base 600 ft (180 m) day/800 ft (240 m) night
visibility 4 km (2.5 miles) day/5km (3 miles) night
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Where fog is forecast, or has been observed within the last two hours within 60 nm of the des-tination or alternate, offshore alternates should not be used.
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Before passing the point of no return (PNR), which should not be more than 30 minutes from the destination, the following actions should have been completed:
– confirmation that navigation to the destination and offshore alternate can be assured;
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radio contact with the destination and offshore alternate (or master station) has been estab-lished;
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the landing forecast at the destination and offshore alternate has been obtained and con-firmed to be above the required minima;
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本文链接地址：飞机管理指南 Aircraft management guidelines(23)
