Definition
Damage to an aircraft, engine, propeller, or related equipment caused by loose objects on the ground or in the airflow path — such as stones, bolts, tools, ramp debris, ice, or birds — being struck by, ingested into, or thrown against aircraft components. The term is also commonly used to refer to the loose objects themselves (foreign object debris) that pose this hazard.
Plain English
Damage caused when stray bits of stuff — rocks, hardware, tools, trash, ice, even birds — get sucked into an engine or hit a propeller, tire, or airframe. The same letters are also used for the loose junk itself.
Context Anchor
Pilots encounter FOD concerns during preflight inspection, engine start, taxi, training on the parking area, and runway operations.
Derivation
The phrase combines three plain English words: ‘foreign’ (not belonging there), ‘object’ (a thing), and ‘damage’ (harm). It became a standard aviation term because even small, out-of-place items can cause large amounts of harm to aircraft, especially to spinning propellers and jet engines.
Why Pilots Care
FOD can cause engine failure or loss of control, directly affecting flight safety.
Intuition Check
Do not read “foreign” as “from another country.” Here, “foreign” means “not belonging there.”
Example Sentence 1
The instructor used the FOD walk before the first flight of the day to show the student how a quick ramp inspection prevents engine and propeller damage.
Example Sentence 2
A missing tool left inside the intake caused FOD during the engine run-up.