Mont. Code Ann. § 67-3-211

Except as provided in 67-3-102, a person may not engage in aeronautics as an aircrew member in this state unless the person has from the department an effective certificate of registration of an appropriate effective aircrew member's license, certificate, or permit issued or approved by the United States government authorizing the aircrew member to engage in the particular class of aeronautics in which the aircrew member is engaged.