MBB-BK 117 All Series
Flight Crew Commercial
Human-Machine Interface; Situational Awareness
Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Provided Assistance; Flight Crew Became Reoriented; General Declared Emergency
Equipment / Tooling; Human Factors; Weather; Procedure
[We] encountered unforecast weather en route. Under Night Vision Goggles (NVG); clouds appeared to be forming near our altitude; but not along our flight path. [I] momentarily flipped up goggles to help in determining if weather conditions were in fact deteriorating along our route. Visibility appeared to be less than forecast; but acceptable; and within minimums. Flipped goggles down; area at 12 o'clock started to appear undefined; but I could still see light sources at 5 miles and beyond; and I could see the horizon. [I] then entered IMC conditions; climbed to MSA; contacted ATC; declared emergency; and asked for vectors to ILS at ZZZ. Just about the same time as being established on the localizer; broke out into VMC. Continued on approach for a few minutes to verify weather conditions warranted canceling IFR clearance. Canceled and returned to base in VMC without further incident. Reported ceilings were OVC 39; forecast conditions were SCT 20; BKN 40. [I] entered IMC at approximately 2;700 MSL or 2;200 AGL. Crew did an excellent job assisting with approach plate and keeping sterile cockpit. Total time in IMC was about 10 minutes. I executed the recovery procedure as directed in the [Operating Manual]. Prior IFR experience helped me to stay calm; but was in no way a factor which caused us to continue flight in deteriorating conditions. Entering the clouds was a surprise. I did not feel prior to entering IMC that I should turn around. There simply were not adequate warning signs. Low experience level with NVG may have been a factor in not being able to accurately determine the base of the unforecast cloud layer.
BK-117 pilot inadvertantly entered IMC; declared an emergency; received vectors for an ILS approach and; once established on the approach entered VFR conditions and returned to base. Pilot believes that low experience level with Night Vision Googles may have been a factor.