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Ditching a helicopter is one of every pilot’s worst nightmares. As if crashing weren’t bad enough, you know you’re enclosed in a rapidly sinking aircraft, disoriented, and likely injured. To make the situation even worse, helicopters almost always flip over upon entering the water (the bulk of the helicopter’s weight, the rotor system, engine, and transmission, are located at the top of the aircraft). So on top of all the aforementioned bad things, you’re upside down. Not good.
Unfortunately for the pilot and passengers of a sight-seeing tour helicopter flying over Pearl Harbor, they had to experience all those. Not far from the USS Arizona Memorial, a Bell 206, a small helicopter that is commonly used in law enforcement, news reporting, aerial tours, and other applications, crashed into the water. Upon ditching, the helicopter flipped over.
From looking at the video, I think I know what caused the helicopter to crash. In my opinion, the aircraft experienced a condition called settling with power, also known as a vortex ring state. In essence, the helicopter, which is disturbing the air with its rotor system, isn’t able to produce enough lift to stay aloft (turbulent air is harder to make lift than in “clean,” less turbulent air), descends into its own downwash. Some of the conditions that contribute to it — near vertical rates of descent of 300 feet per minute or more, slow forward airspeed, and the aircraft using high amounts of available power (as one might in a high hover), hovering outside of ground effect steep approaches at high rates of descent, etc. — are apparent in the video below.
It depends on the specific situation you find yourself in, but generally speaking, to escape settling with power you want to push the cyclic forward to gain airspeed to escape the ring vortex, which I’m sure the pilot tried to do. Unfortunately, any steps he took to keep the aircraft from descending did not work, as you can clearly see. Fortunately, the crash occurred near the shore. Folks nearby were able to help remove the occupants from the helicopter. As of now, one is in critical condition, but all five people on board made it out alive. Hopefully, they’ll all make a speedy recovery.
Sorry for the aerodynamics/theory of rotary wing flight lesson there, guys. That stuff was beaten into my head a while back, so it kind of rolls of the tongue now..