Plain English Meaning
The Plan is everything you intend to do on this flight — where you are going, how you are getting there, the weather you expect, the fuel you have, and your backup options. It is the first item the pilot checks at each decision point in the 5P check.
Full Definition
In the 5P checklist used in Single-Pilot Resource Management, the Plan is the first P. It refers to the overall mission of the flight: the route, weather, fuel, alternates, NOTAMs, and any other elements that make up the intended conduct of the flight from departure to arrival. The Plan is reviewed and updated repeatedly during the flight, not just once before takeoff.
Context Anchor
Used during preflight planning and repeated in flight as part of the 5P check: the Plan, , the Pilot, , and .