A company may enter into a related party lease for several reasons, including FAA regulations, state sales tax planning, risk management, and sharing use of an aircraft. For rental of wide-body or turbine aircraft, requires a written rental agreement. “A copy of the lease must be carried on board. Government Aircraft - A federal aircraft, that is, an owned or borrowed aircraft or a commercial aircraft leased as a CAS aircraft. ISSA Interservice Support Agreement - Any agreement between two or more executive agencies in which an agency agrees to provide aviation support services, that is, to operate an aircraft and provide other aviation support services. aviation,