Thomas Coupling
G0ULI (golf zero uniform lima india) happens to be my radio callsign, although I admit it might be deemed unfortunate in the context of this subject. I have fixed wing flying experience and attended the scene of a fatal light aircraft crash in a professional capacity many years ago, which prompted a lifelong interest in flight safety. I was mystified as to what set of circumstances could cause an apparently perfectly functional helicopter to fall out of the sky. It would seem from the answers in this forum and information elsewhere that something such as a vortex ring formation could in theory put a helicopter in such an attitude that the engines would stop from fuel starvation and in that event, the pilot would have very little time to recover the aircraft. I never knew that the main rotor rpm had to be constrained to within such tight limits or fully appreciated that a full main rotor stall would be unrecoverable irrespective of altitude. This thread has been most enlightening, irrespective of some of the irreverent comments. I have had several opportunities over the years to take a flight in a police helicopter, I never took up the offer, although friends thought I was mad not to. I will stick to fixed wing aircraft.