Helicopter pilots unexpectedly straying into IFR conditions and losing control of their aircraft has been identified as the cause of the greatest number of rotorcraft fatalities, according to the International Helicopter Safety Team (IHST). The group, which is focused on greatly reducing helicopter accidents by 2016, has reported that NTSB figures from 2011 indicate that 45 of 52 such accidents proved fatal to occupants. “That means the chances of surviving an inadvertent encounter with IFR are just 14 percent,” according to the IHST. Helicopter experts say inadvertent IMC encounters are some of the most demanding, disorienting and dangerous conditions a pilot can experience. Initial flight training for helicopter pilots does include some maneuvers under simulated IMC, just as it does for fixed-wing aviators. The IHST has reminded operators that helicopter IMC training should include, at a minimum, how to positively determine en-route weather, how to avoid IMC conditions in the first place, in-flight weather abort procedures and recovery from inadvertent IMC encounters. The use of flight simulators is highly encouraged so pilots can remain current enough to cope with inadvertent IMC safely. Pilots should remain even more vigilant at night for signs of deteriorating weather, such as the need to descend lower than planned and the loss of ground references.