Sikorsky VH-34 Sea Horse USMC helicopter model. U.S. Marine Corps helicopter Sqn. One (HMX-1) and the U.S. Army Executive Flight Detachment have as a primary mission the emergency evacuation of the President, his family, and other key government officials. After satisfying this mission, these units furnish helicopter transportation for the President and others. In 1961, the VH-3D Sea King began to replace the VH-34D as the primary executive transport.