The NTSB has issued its final report on the fatal Aug. 12, 2017 crash of a Virginia State Police (VSP) Bell 407 helicopter that killed both crewmembers. While not listing a probable cause, the report presented data suggesting that failure to avoid and recover from settling with power, also known as vortex ring state, might have been a factor.
This condition produces uncommanded pitch and roll oscillations and little or no collective authority that can quickly produce descent rates of nearly 6,000 fpm. The aircraft was observed in a rapid descending spin before impact. “The helicopter’s low forward speed while descending put it in or near a region conducive to a vortex ring state,” according to the NTSB, explaining that this occurred in a downwash in which the descent rate could not be arrested with increased collective.
According to the NTSB, the VSP flight training manual did not include specific lesson plans dealing with vortex ring state. It added that “associated maneuvers were considered to be optional” and a review of the pilot’s records “found no record of him receiving settling with power or vortex ring state recognition and recovery training on the accident helicopter make and model.” This was despite the fact that the FAA’s test standards require the pilot to understand, recognize, and be able to use the appropriate recovery from the condition.