Definition
Flight in which the load on the aircraft and its occupants equals the normal pull of gravity — that is, the wings are producing lift equal to the weight of the airplane. This is the condition during straight-and-level unaccelerated flight.
Plain English
The airplane feels its normal weight. The wings are lifting just enough to hold it up — no more, no less. You feel the same as you would standing on the ground.
Context Anchor
Seen in stall discussions when comparing a normal stall to a stall that happens under extra maneuvering force.
Derivation
The 'G' stands for the acceleration due to gravity. '1 G' means one times normal gravity — the everyday pull you feel standing on the Earth. In flight, it describes the loading on the aircraft, not the speed or altitude.
Why Pilots Care
Stall speed is defined for 1 G flight; any increase in load factor raises the speed at which the wing stalls.
Grounding Statement
Straight-and-level cruise on a calm day is 1 G flight — you feel your normal body weight in the seat.
Intuition Check
Do not read “1 G” as a speed, altitude, or airplane model. Here it means normal gravity force: one times the airplane’s weight.
Example Sentence 1
During cruise at a steady altitude and heading, the airplane is in 1 G flight and the published stall speed applies.
Example Sentence 2
Once the pilot banks steeply the airplane leaves 1 G flight and the stall speed begins to rise.