Inability of an individual or a group to perform the given tasks up to the established standards. http://www.businessdictionary.com/definition/deficiency-performance.html.
TSA Requirements. The TSA requires that adult passengers ages 18 and older show valid photo ID at the security checkpoint. Children, however, are not required to present such identification. This does not mean, however, that children will be able to fly without it.
Children under the age of 16 do not need to show ID on domestic routes. The adult they are travelling with can vouch for the infant's/child's identification, providing the relevant photo ID is shown (by the adult). On International routes a passport will be required.