Definition
The maximum positive load factor, expressed in Gs, that an aircraft is certified to withstand without suffering structural damage. On a Vg diagram, it is shown as a horizontal line at the top, marking the upper boundary of safe maneuvering loads at a given airspeed.
Plain English
The highest upward G-force the aircraft is approved to handle before its structure could be damaged. Pull harder than this and you risk bending or breaking the airframe.
Context Anchor
Seen on the Vg diagram in discussions of maneuvering speed, steep turns, pull-ups, turbulence, and structural operating limits.
Derivation
Positive' here means upward-acting load (pushing the pilot down into the seat). 'Limit' means the boundary set by certification — the most the structure is approved to take in normal operation, with a safety margin above it before actual failure.
Why Pilots Care
Exceeding this value during maneuvers can cause permanent airframe damage or failure.
Grounding Statement
In a hard pull-up or steep turn, the wings may have to hold up much more than the airplane’s normal weight; the positive limit load factor is the approved upper number for that extra load.
Intuition Check
“Positive” does not mean good or safe by itself; it means the loading acts in the normal upward-lift direction. “Load” does not mean baggage or cargo here; it means force on the aircraft structure.
Example Sentence 1
The Cessna 172 in the normal category has a positive limit load factor of 3.8 Gs, so a steep turn at full gross weight must stay well within that limit.
Example Sentence 2
The V-g diagram shows the positive limit load factor as the upper boundary of the normal operating envelope.