Definition
The greatest total lifting force a lighter-than-air aircraft is permitted to develop, equal to the weight of the air it displaces minus the weight of the lifting gas inside its envelope, up to the certificated limit set for that aircraft.
Plain English
The biggest amount of upward force a balloon or airship is allowed to produce. It is the difference between the weight of the air pushed aside and the weight of the lighter gas inside, with a fixed ceiling that the aircraft is approved to operate at.
Context Anchor
Seen in balloon weight-and-lift calculations, aircraft limitations, and preflight planning for balloon operations.
Derivation
‘Gross’ here comes from the Old French gros, meaning ‘whole’ or ‘total before deductions.’ In aviation it signals the full, unreduced figure — total lift before subtracting the aircraft’s own weight, fuel, crew, or payload.
Why Pilots Care
Exceeding this weight reduces climb performance, increases stall speed, and can damage the airframe or prevent a safe takeoff.
Grounding Statement
Before flight, the pilot must make sure the balloon’s total required lift stays at or below the approved limit.
Intuition Check
Do not read gross lift as extra lift or payload lift. Here, gross means total lift for everything the balloon must support.
Example Sentence 1
Before the flight, the crew checked the gas purity and ambient conditions to confirm the airship would not exceed its maximum allowable gross lift.
Example Sentence 2
On a hot day the maximum allowable gross lift dropped enough that two passengers had to be left behind.