Bell Helicopter Textron Undifferentiated or Other Model
Flight Crew Commercial; Flight Crew Instrument
Flight Crew Last 90 Days 50; Flight Crew Total 5826; Flight Crew Type 200
Distraction
Inflight Event / Encounter VFR In IMC; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Issued New Clearance; Flight Crew Requested ATC Assistance / Clarification
Aircraft; Human Factors; Weather
Operating as an air ambulance; I was en route at 2;000 FT MSL in cruise flight heading south to the hospital for a patient pickup. I was following an advancing cold front with thunderstorms well to my east. I had just made contact with Approach informing the Controller of my intentions of landing at the hospital. I was flying under NVG's and noticed that I lost outside visual reference. I called Approach and told them I had entered IFR conditions. The Controller immediately gave me vectors for a GPS Approach to the local airport. I never declared an emergency. I started a right descending turn and broke-out of the cloud/fog layer at approximately 1;600 FT MSL. I notified the Controller that I was VFR again and would like to continue my flight to my destination. I was in IFR conditions for no more than 2 minutes. I had no further incidents after that encounter. I would say that the lightening flashes from the thunderstorm to my east were distorting my view in the NVG's; causing me to not see the cloud/fog layer.
Helicopter pilot reports entering IMC inadvertently at night while using NVG's. Lightening flashes from a thunderstorm ahead had prevented visual detection of a fog bank.