When should a pilot not fly through marginal weather when diverting?

A pilot should avoid flying through marginal weather when fuel does not permit safe recovery because safety is paramount in aviation operations. Insufficient fuel compromises a pilot's ability to divert to an alternate airport or return to the original departure point if necessary, especially in challenging weather conditions. When a pilot knows that fuel levels are low, it heightens the risk of being unable to reach a safe landing location if difficulties arise during flight. Thus, ensuring that there is an adequate fuel reserve is critical for maintaining safety, especially in adverse weather where the situation can rapidly become more complicated.

In situations where other options, such as adequate fuel (allowing for flexibility in navigation), visibility of other aircraft, or prior clearances, are somewhat less critical than ensuring that a pilot has enough fuel, the priority remains on the aircraft's operational safety. Therefore, a decision not to enter marginal weather conditions when fuel does not allow for safe recovery reflects sound judgment in aviation practice.