§ 135.95 – Airmen: Limitations on use of services.
(a) No certificate holder may use the services of any person as an airman unless the person performing those services—
(1) Holds an appropriate and current airman certificate; and
(2) Is qualified, under this chapter, for the operation for which the person is to be used.
(b) A certificate holder may obtain approval to provide a temporary document verifying a flightcrew member's airman certificate and medical certificate privileges under an approved certificate verification plan set forth in the certificate holder's operations specifications. A document provided by the certificate holder may be carried as an airman certificate or medical certificate on flights within the United States for up to 72 hours.