Rescue swimmer is a designation given to rescue specialists, most commonly in the service of the military. Rescue swimmers usually are charged with the rescue, assessment, and rendering of medical aid to persons in distress in the sea, on the land, or in the air. This highly specialized position is extremely challenging. United States U.S. Coast Guard Arguably the most widely recognized team of rescue-swimmer operators, the elite United States Coast Guard Aviation Survival Technician (AST)/Helicopter Rescue Swimmer team is called upon to respond in the most extreme rescue situations. High seas, medical evacuations, downed aviators, sinking vessels, and hurricanes are some of the deadly scenarios that Coast Guard rescue swimmers are trained to handle. The Coast Guard's team of ASTs is composed of about 350 active-duty members, and just over 1000 members have passed the training to become Helicopter Rescue Swimmers since the mid-1980s. The training school has one of the highest attrition rates of any military school with about 80% of candidates washing out. For comparison, the attrition rate for United States Navy SEAL selection and training is about 75% AST School in Elizabeth City, North Carolina lasts for 24 weeks, and includes intense physical fitness, long hours of pool fitness and instruction, extreme water-confidence drills, and classroom instruction. The Coast Guard rescue swimmer training program is very challenging and is one of the toughest U.S. military training courses. Reportedly, only 75–100 Coast Guard personnel attend the school each year. The attrition rate in some years has been as high as 85%, although the 10-year average is just over 73%. Prospective U.S. Coast Guard rescue swimmers are physically conditioned to meet high physical fitness standards. About half of prospective candidates make it to AST "A" School. Upon graduation, candidates must attend seven weeks of training at the Coast Guard's Emergency Medical Technician (EMT) school in Petaluma, California, where ASTs become EMT qualified. Rescue swimmers at Coast Guard Air Station Sitka, Alaska, must maintain the EMT-Intermediate level of proficiency due to the remoteness of their operational area and the number of medical evacuations performed by that unit each year. Once stationed at a Coast Guard Air Station, apprentice ASTs must complete 6 months of qualification on their respective airframe before moving on to finish their rescue swimmer syllabus and becoming journeymen. The Coast Guard holds a one-week Advanced Helicopter Rescue School (AHRS, formerly known as Advanced Rescue Swimmer School)