RedactedNarrative: Summary:  
  A recreational boat backed slowly into a swimmer causing severe injury due to a propeller strike.  This accident was likely caused by the operator placing the boat into reverse unintentionally when he meant to place it into neutral, and also by the operator failing to notice that the vessel was backing up due to outside distractions.
  
  Details of the incident:
  While on aerial patrol over Lake Mead on 9/3/2017 at approximately 13:49 hours I received a request from NPS dispatch to respond to a medical emergency at the Echo Bay Marina. The report was of a 21 year old female who was struck by a boat propeller who sustained deep lacerations across her hip and lower back. I responded to Echo Bay, and while I was in route NPS Volunteer Vessel arrived on scene to begin assessing the patient and to control bleeding. There were two volunteers aboard 66V, and was the lead volunteer that was attending to the patient when I arrived.
  I landed on the water at the Echo Bay Marina at approximately 14:06 hours, and then taxied to the shore adjacent to the boat launch courtesy dock where I tied up the airplane. I found the patient lying on her stomach on the swim platform of the boat that struck her which was tied up to the courtesy dock. Bleeding was controlled and the patient appeared to be breathing adequately and speaking coherently. Witnesses (brother) and  (father) stated that the accident happened out in the lake nearby, and that they transported her to the courtesy dock on the back of the boat. 
  There was not adequate radio reception from the Echo Bay boat launch area, so an accurate patient update had not yet been given to dispatch and other responding units. I called dispatch via satellite phone to give a patient update, and then returned to the patient to start taking vital signs and to conduct a more thorough medical assessment. Before I had completed taking a blood pressure and pulse rate, EMT''s from a Clark County ambulance arrived on scene and took over primary care of the patient (see EMS Charts patient care report 47474427). The Clark County crew later transferred patient care again to the crew of the Mercy Air helicopter that had landed on the Echo Bay boat launch helipad shortly after the Clark County crew''s arrival. 
  Operator stated that he was driving the boat before the incident, pulling his sister Victim behind on an air-chair before he stopped the vessel and attempted to put the engine into neutral. Both Operator and his father stated that the gear selector of the boat was very sensitive between reverse and neutral, and that it is not easy to tell on their boat if the engine is truly in neutral or at idle in the reverse gear. Operator stated that he and his father were distracted taking photos of a nearby boat, and that he thought that victim was swimming safely off to the side of the boat. Operator stated that he likely had placed the boat into reverse gear on accident, and that the boat backed slowly into victim while nobody was paying attention. After victim was struck by the propeller they loaded her onto the swim platform and transported her to the nearby Echo Bay boat launch where they were first met by NPS volunteer boat 66V, and then later by me. See Report Beam Vessel Accident Report.
  After victim was loaded onto the helicopter I finished interviewing witnesses Operator and father, and collected vessel registration information, vessel photographs, and witness statements from the two of them. All units were clear of the scene at approximately 15:15 hours.
  
  End of report