MBB-BK 117 All Series
Confusion; Distraction
Flight Deck / Cabin / Aircraft Event Other / Unknown; Inflight Event / Encounter Weather / Turbulence; Inflight Event / Encounter Object
Flight Crew Diverted; General Flight Cancelled / Delayed
Human Factors; Weather; Aircraft
We were dispatched to a scene to pick up a patient to take north. The weather at the site was showing 4;300 and 10 miles and had been improving throughout the day. Weather at the destination was VFR with 10 miles visibility below the ceiling. There were no radar returns on the weather display before the launch.After loading the patient at the scene we started north. After about five minutes of flight I noticed that the weather was coming down and there was an increase in haze and water vapor. We still had three plus miles of visibility but it was not what we started with.  I set the radar bug at 500 feet for a little extra altitude and slowed up a bit. I started a left turn toward better weather when we encountered a sudden light/moderate shower that hadn't been there an instant before as best I can describe it. The water on the windshield reduced my ability to see out the window. I continued my left turn into a 180 degree turn because we had good visibility in that direction and headed back. At the same time I informed the med crew that it wasn't possible to get to our destination because of the weather. We decided that we needed to land and transfer the patient to an ambulance.  We landed at a nearby hospital. The patient was transferred; the med crew went with him; and I flew back to base.I waited until the med crew got back so we could debrief. During the debrief the med crew told me that we passed low over an antenna. I did not see any antennas; nor do I know of any antennas at our altitude in that general area. The radar altimeter was set and it never alarmed.I am raising my launch minimums at the destination airport to take flights in the daytime to help ensure more favorable weather along the route. There was no indication on the weather computer that this weather was out there. Possibly because of the semi hilly territory.This particular aircraft has an older GPS navigation system which is without a moving map display. It does not track the closest user waypoints (such as hospitals) on the moving map. To enter a waypoint requires scrolling through a long column of waypoints with a variable speed cursor; which can be delicate to do. This results in greater head down time when compared to a moving map Garmin.
A medical helicopter flight to transfer a patient was diverted due to weather.  The patient was transferred to a ground ambulance.