FAR 91.167 -
(a) No person may operate a civil aircraft in IFR conditions unless it carries enough fuel (considering weather reports and forecasts and weather conditions) to -
(1) Complete the flight to the first airport of intended landing;
(2) Except as provided in paragraph (b) of this section, fly from that airport to the alternate airport; and
(3) Fly after that for 45 minutes at normal cruising speed or, for helicopters, fly after that for 30 minutes at normal cruising speed.
(b) Paragraph (a)(2) of this section does not apply if:
(1) Part 97 of this chapter prescribes a standard instrument approach procedure to, or a special instrument approach procedure has been issued by the Administrator to the operator for, the first airport of intended landing; and
(2) Appropriate weather reports or weather forecasts, or a combination of them, indicate the following:
(i) For aircraft other than helicopters. For at least 1 hour before and for 1 hour after the estimated time of arrival, the ceiling will be at least 2,000 feet above the airport elevation and the visibility will be at least 3 statute miles.
Este regulamento (91.167) aplica-se a aeronaves civis, independentemente do equipamento utilizado para navegação (por exemplo, GPS / WAAS).
No entanto, se a sua aeronave tiver um GPS instalado e operado corretamente (consulte os requisitos do TSO nas referências da AIM / AC abaixo), você pode planejar o voo até o seu destino e alternar da seguinte forma:
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TSO-C129 () e TSO-C196 () equipado ( aeronave GPS ) - ou o destino ou alternativo, mas não ambos, pode oferecer apenas um GPS abordagem (nenhum outro tipo de abordagem precisa estar disponível)
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TSO-C145 / -C146 ( Aeronave Equipada com WAAS ) - Tanto o destino e o alternativo pode ser aeroportos com apenas abordagens de GPS disponível.
Referências: OBJETIVO 1-1-17 b 5 c / d, 1-1-18 c 9 a. AND AC-105A, parágrafo 9.5.1