Definition
A unit of weight in the U.S. customary system, equal to 16 ounces or approximately 0.454 kilograms. In aviation, pounds are the standard unit used to express aircraft weights, fuel quantities, payloads, and thrust.
Plain English
A measure of how heavy something is. One pound is a little less than half a kilogram.
Context Anchor
Seen in aircraft weight and balance information, aircraft manuals, loading notes, and performance calculations.
Derivation
From the Latin libra, meaning 'scales' or 'balance' — which is also why the abbreviation is LB rather than PD. The same root gives us the British currency symbol £.
Why Pilots Care
Aircraft maximum gross weight, empty weight, and center-of-gravity limits are expressed in pounds. Overloading or miscalculating these values directly affects takeoff performance, stall speed, and structural safety.
Intuition Check
Do not read LB as a volume such as gallons. In this context, LB is a weight amount in pounds.
Example Sentence 1
The aircraft's maximum takeoff weight is 2,550 lb.
Example Sentence 2
Adding 60 LB of baggage shifted the center of gravity beyond the aft limit.