Definition
Fixed weight installed in an aircraft at a specific location to bring its empty-weight center of gravity within allowable limits, or to maintain it there after equipment changes. Permanent ballast is secured so it cannot shift in flight, is marked to identify it as ballast, and is recorded in the aircraft's weight and balance records. It remains with the aircraft and is not removed for normal operations.
Plain English
A fixed weight bolted into the aircraft to keep its balance point in the right place. Once installed, it stays there as part of the aircraft.
Context Anchor
Seen in aircraft weight-and-balance records, equipment lists, and maintenance discussions after equipment is added, removed, or relocated.
Derivation
Ballast comes from an old Scandinavian word meaning a heavy load carried by a ship to keep it stable in the water. In aviation it means the same thing — added weight to keep the aircraft balanced — and 'permanent' simply distinguishes it from temporary ballast that is loaded and unloaded for individual flights.
Why Pilots Care
It keeps the center of gravity within safe limits without depending on removable weights that could be forgotten or misplaced.
Intuition Check
Do not treat permanent ballast like baggage or cargo. It is installed weight that is already part of the aircraft’s recorded weight unless maintenance records show it was properly changed.
Example Sentence 1
After the older radios were replaced with lighter avionics, the mechanic installed permanent ballast in the tail to keep the empty-weight center of gravity within limits.
Example Sentence 2
Records showed twenty pounds of permanent ballast installed to keep the empty weight and balance within limits.