FOD, standing for Foreign Object or Debris, refers to anything that is foreign to the aircraft or abnormal to its operational environment such as baggage tag or wheel, wooden chock splinter, tool, safety wire, GSE parts, pavement debris, catering supplies, cabin cleaning garbage, plastic or paper wrappings and so on.

FOD represents a major threat for the Air Transport Industry and particularly airports, airlines and ground handling companies. FOD may cause damage to equipment, including the aircraft itself e.g. by engine ingestion, but also, through jet blast projection, it may injure personnel like airport or airline workers as well as passengers or any person in the vicinity.

Furthermore the growing presence of composite materials in aircraft fuselage and structure dramatically increases the consequences of FOD damage to these parts as, what would have been an otherwise minor impact on a metal surface, may now lead to invisible and unreported composite delamination with its severe consequences on a pressurized vessel.

The overall cost resulting from FOD damage ranges annually in the billions of US dollars worldwide as it concerns not only direct costs for repairs but also indirect costs such as flight delays and cancellations, aircraft unserviceability (AOG), fuel dumping, passengers accommodation and re-booking, and of course all liabilities with their impact on insurance costs.