Both Winnerhofer and Jim59 raised use of Fenestron or tail rotor guards. Those thoughts also came to mind when I read about this sad incident. Various helicopter manufacturers have certainly been conscious of the risks related to injury from the tail rotor, and it didn't take any regulations for them to factor this into their designs. Given the Gazelle was the first helicopter to feature the Fenestron, I read on Wikipedia what it said about this feature: "The fenestron, while requiring a small increase in power at slow speeds, has advantages such as being considerably less vulnerable to damage, safer for people working around the helicopter and with low power requirements at cruising speeds, and has been described as "far more suitable for high-speed flight"...". Of course mounting the tail rotor high on a vertical stabilizer such as on the MBB Bo 105 and BK 117 are other options that have been adopted, especially considering their rear loading clamshell doors. NOTAR had also already been mentioned as another way of preventing injury. Again, Wikipedia entry for NOTAR mentions benefits of "increased safety (the tail rotor being vulnerable), and greatly reduced external noise". Then there are also coaxial and tandem rotor helicopters which also dispense with the need for a tail rotor. I wonder whether there would be any rational way of comparing ground accident/injury statistics for helicopters were there is no tail rotor within reach against types where there is such a risk?