INDIAN HEAD, Md. - A Marine with the Chemical Biological Incident Response Force, prepares to execute a midpoint drop at the Naval Support Facility Indian Head April 19. The midpoint drop is utilized when there is an area that cannot be safely accessed by walking, as in the case of a ravine. The technical rescue Marine must first traverse across a highline that is established at two point at the top of the ravine. He is then lowered via a pulley sytem to retrieve the patient. - INDIAN HEAD, Md. - A Marine with the Chemical Biological Incident Response Force, prepares to execute a midpoint drop at the Naval Support Facility Indian Head April 19. The midpoint drop is utilized when there is an area that cannot be safely accessed by walking, as in the case of a ravine. The technical rescue Marine must first traverse across a highline that is established at two point at the top of the ravine. He is then lowered via a pulley sytem to retrieve the patient.