On December 16, 2003, at 1908 eastern standard time, a MBB, BK117A3, N911WJ, registered to Merrill Lynch Business Financial SE, operated by C J Systems Aviation Group Inc., as a 14 CFR Part 91 positioning flight, collided with trees and the ground during an inadvertent encounter with instrument flight conditions in cruise flight. No flight plan was filed and a computer weather briefing was obtained. The helicopter sustained substantial damage. The commercial pilot and two paramedics reported minor injuries. The flight originated from a heliport located at Sebring Hartland Hospital, Sebring, Florida, on December 16, 2003, at 1850. The pilot stated he departed the hospital, climbed to 1,000 feet, and was in visual flight conditions on a heading of 120-degrees magnetic with a ceiling of 1,500 feet and 8 to 10 miles visibility. He passed Okeechobee to the northeast and encountered instrument meteorological conditions (IMC). He observed some highway lights to the east and started a left turn to get a reference on the lights and "lost total visibility due to heavy rain". He slowed the helicopter down and lost sight of the lights. He made a right turn to the south and "encountered vertigo". He immediately looked down at his flight instruments and observed the artificial horizon was above the horizon, and the airspeed was decreasing. He lowered the nose of the helicopter to regain airspeed and the helicopter began to settle. The nose of the helicopter went to the right and down. He looked back at his flight instruments, the attitude indicator showed the helicopter was inverted, and the vertical speed indicator indicated a 1,000-foot a minute descent. He immediately applied cyclic pitch and rolled the helicopter to the upright position and pulled collective pitch to increase power. The front seat paramedic made a mayday call on the radio. The helicopter collided with the trees in an upright position and fell to the ground. The pilot stated there were no mechanical deficiencies with the helicopter. A paramedic located in the left front seat of the helicopter stated they had just cleared a rain shower when the pilot stated he wanted to follow State Road 70 due to the headlights of the cars. It was dark except for the lights of a few distant houses and the lights of the cars. The pilot started a turn. "During this bank our descent became increased and sharp." He reached over and grabbed the pilot's leg and said his name three times with no response. "We then came to a level attitude and began to fish back and forth from nose to tail and back. This increased in intensity until we entered a right hand downward spiral and impacted the ground." A St. Lucie County Sheriff's helicopter pilot dispatched to search for the accident helicopter stated he encountered increasingly deteriorating weather and they were using night vision goggles (NVG) which allowed them to continue at a reduced airspeed. The ceiling was 500 feet with light to moderate rain showers and the visibility with NVG's was 3 to 5 miles. They descended down to 300 feet and observed a "black line of low level scud to the northeast about a 1/2 mile away." They started receiving emergency locator signals while they were conducting a grid search. They turned off their anti-collision strobes due to the light refracting the flashes in their NVG's. They immediately observed a light source about a mile away. They flew towards the light source and located the downed helicopter. Training records provided by CJ Systems Aviation Group revealed the pilot received training on inadvertent IMC on October 6, 2000. The training syllabus states that every pilot is authorized one hour of inadvertent IMC flight training per quarter. The Inadvertent Instrument Meteorological Conditions Checklist (IIMC) instructs the pilot to: 1. FLY THE AIRCRAFT 2. CLIMB TO ALTITUDE 3. DO NOT GET IN A HURRY 4. CONTACT APPROACH or CENTER "The first three items should be committed to memory." The pilot had 200 hours in the BK117A3, and no actual instrument flight time. Review of FAA Advisory Circular 60-4A, PILOT"S SPATIAL DISORIENTATION, states, "The attitude of an aircraft is generally determined by reference to the natural horizon or other visual references with the surface. If neither horizon nor surface reference exists, the attitude of an aircraft must be determined by artificial means from the flight instruments. Sight, supported by other senses, allows the pilot to maintain orientation. However, during periods of low visibility, the supporting senses sometimes conflict with what is seen. When this happens, a pilot is particularly vulnerable to disorientation. The degree of disorientation may vary considerably with individual pilots. Spatial disorientation to a pilot means simply the inability to tell which way is up.