@@maximeresch9767 per 121.617, the specified alternate need only meet the alternate weather requirements per the carrier’s operation specifications (which could require two separate runways and two unique approach frequencies IF the carrier has the common authorization to derive alternate weather minimums (to permit a lower ceiling/visibility to qualify the airport as an alternate). Otherwise, a specified alternate doesn’t automatically require two available runways. Check out my other video, which addresses alternate weather minimums (for anytime an alternate is required, whether it be for destination purposes or for takeoff purposes. The same minimum weather conditions to qualify an airport for use as any kind of alternate is the same).

If both the latest weather report (METAR) and forecast (TAF) do not indicate at least 3SM AND at least 2,000 ceiling for period one hour prior to one hour after destination ETA. If either of those weather products indicates a visibility less than 3SM OR a ceiling less than 2000, an alternate must be specified. Any conditional language (tempo, prob, becmg, must be considered if time frame covers any portion of the +/- 1 hour ETA.

In the absence of an ops spec authorization to permit less than applicable minimum weather in such conditional statements, with regard to qualifying an airport as an alternate, the applicable minimum weather must be reflected in the forecast at the alternate ETA. There can be nothing lower than the full applicable minimum ceiling and minimum visibility in the portion of the forecast that covers the alternate ETA. For example, if the applicable alternate minima is 600/2, a probability or tempo that contains anything less than either one of those minimum values, would disqualify the airport under consideration for an alternate (at least at that ETA), since both prob and tempo statements are indicators that the ceiling and/or visibility could be less than required. Technically, a delayed departure time, which would result in a later destination ETA (therefore a later alternate ETA) may yield a different line of the forecast which would fully satisfy applicable alternate minimums. A more solid alternate (with better than minimum applicable weather) is a more prudent plan, when possible. See §121.631 (b) for the logic. Any new forecast issued throughout the flight must reflect at least the minimum applicable weather criteria for any specified alternate. Avoid violation of §121.631 by initially specifying an alternate with better than minimum weather, and monitoring new forecasts issued during the flight. Standard TAF issue times are 0000, 0600, 1200, and 1800z.

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