When is an alternate airport required during an IFR flight?

An alternate airport is required during IFR (Instrument Flight Rules) flight to ensure safety in situations where landing at the intended destination is not possible, particularly due to poor weather conditions or other factors that may arise unexpectedly.

The requirement for an alternate is based on the weather forecast for the destination airport before and during the flight. If the forecast shows that the weather conditions will be below minimums for landing at the destination (for example, forecast visibility is below the required minimums for the approach type available), then an alternate must be designated.

While the notion of NAVAID compatibility is crucial, it is primarily the weather conditions that dictate whether an alternate airport is necessary. In fact, the regulations specifically require that if the destination airport does not have suitable approaches or if the weather is forecasted not to meet the landing criteria, an alternate must be selected to mitigate risks associated with potential alternate landing scenario needs.

As for the other scenarios, an alternate is not required merely because the destination lacks landing facilities, if video operations are intended, or under certain weather conditions where flight rules permit landing without an alternate planned. The determination of whether an alternate is required hinges significantly on the overall risk assessment due to weather and potential operational challenges.