Instrument flight rules (IFR) demand proficiency in specialized charts like En Route, STARs, SIDs, and Approach Plates, which are crucial for safe navigation in instrument meteorological conditions ...
A "pop-up" is an on-the-spot IFR clearance from Air Traffic Control (ATC), often granted without a pre-filed flight plan or briefing, serving as a vital safety option to avoid hazardous scud running.