On December 31, 1997, at 1625 eastern standard time, an Aerospatiale AS-355 helicopter, N355DS, was substantially damaged during collision with a building while landing at the West 30th Street Heliport (JRA), New York, New York. The certificated commercial pilot and three passengers were not injured. Two other passengers in the helicopter and two persons on the ground received minor injuries. Visual meteorological conditions prevailed for the sightseeing flight that originated at JRA at 1612. No flight plan was filed for the flight conducted under 14 CFR Part 91. According to an FAA Aviation Safety Inspector, the helicopter had completed a sightseeing tour with the pilot and five passengers on board. The helicopter approached the heliport from the northwest with a tailwind and was cleared to land on the "Transient" pad at JRA. The helicopter over flew the Transient pad and collided with the Control Room Building at the heliport. In a written statement, the pilot reported: "When I started to pull collective to terminate the approach, the aircraft started to settle fast. At that point, I was too close to fly out of it so I tried to keep the aircraft level and steered slightly right. The aircraft still settled and then I came over the bulkhead. I tried to pull more collective to stop it. Since I was in ground effect, that was the last thing I could try to stop it. [The] aircraft contacted the ground and skidded until the aircraft contacted the building." In written statements, witnesses stated the helicopter approached the landing site from the northwest. From inside the control room they watched the helicopter "...overshoot the assigned landing spot..." and vacated the room prior to the helicopter's collision with the building. One witness stated, "The pilot did not indicate any control problems with the helicopter." According to the United States Army Field Manual 1-203, Fundamentals of Flight, "Settling with power is a condition of powered flight in which the helicopter settles in its own downwash...Conditions conducive to settling with power are a vertical or near-vertical descent of at least 300 feet per minute and low forward speed...These conditions can occur during downwind approaches...steep approaches...and hover [out of ground effect]....If not enough power is available for recovery, applying collective pitch may aggravate power settling." The pilot reported that there were no mechanical deficiencies with the helicopter. At the time of the accident, the winds reported at JRA were from 290 degrees at 15 knots gusting to 25 knots.