WPR13LA025 · Robinson Helicopter Company R22 MARINER

Both the pilot and copilot of the helicopter were employed by and operating for a company that photographed boats in motion. The typical procedure was to fly low and slow on a path parallel to, and in the same direction as, the target boat; pass the boat; make a climbing 180-degree course reversal turn around the bow of the boat; and then descend and proceed to the next boat. During their second flight of the day, while nearing the completion of the course reversal turn to the right after a photo pass, the pilot initiated the descent for the next photo pass. The pilot added power and collective pitch to arrest the descent; however, he was unable to do so before the helicopter impacted the water. Although the tail boom was not recovered, no evidence of any preimpact failures with the helicopter was observed in the recovered wreckage.

The course reversal turn was made from north to south, and the wind at an airport 17 miles to the northwest was out of the north at 15 knots. The pilot reported that the wind was about 12 knots gusting to 17 knots and that "clear air turbulence" was present. Although the exact wind conditions at the accident site were not known, evidence indicated that the helicopter experienced an overall wind change from a 12- to 15-knot headwind to a similar magnitude tailwind during the course reversal turn. Given the low speed of the photo pass, it is likely that the pilot did not correctly compensate for the wind speed and direction change during the course reversal and that the helicopter entered a vortex ring state (settling with power) due to the combination of low forward speed and the tailwind. The pilot's perception of, or attention to, the airspeed could have been adversely affected by his extra-cockpit focus on locating and tracking target boats.

The pilot's attempt to arrest the descent by adding power and collective pitch was not the proper technique for recovery from the vortex ring state, but no evidence suggests that the pilot even recognized the onset of that condition. However, even if he did recognize its onset, the helicopter's altitude was likely too low to safely exit the vortex ring state because proper recovery from that state requires increasing the airspeed and/or lowering the collective pitch, which respectively either requires or results in a temporarily increased descent. Further, it is likely that the pilot was operating in a region of the height-velocity chart such that an autorotation would not have been successful.

Verbatim NTSB analysis and probable cause from the NTSB dataset