Background
The pilot and passenger departed on a local flight from a boat roof helipad. After a short flight, they landed in a restaurant parking lot. At 2125, on a moonless night with an overcast sky, they departed the parking lot for the 1-mile flight back to their helipad.
Accident Sequence
On final approach, the pilot slowed the helicopter and descended into the water, about 500 feet short of the pad. The pilot and passenger exited the helicopter, but only the passenger was rescued by boat.
Examination
Examination of the helicopter and engine revealed no pre-impact failures. The passenger stated that she heard no abnormal noises, nor observed any of the helicopter's caution panel lights prior to water contact.
Pilot Experience
The pilot had accumulated about 150 hours of total flight experience, all in this make and model helicopter.
Helipad and Environmental Conditions
The boat roof helipad was not lighted. A single flood light under the roof illuminated a jet-ski. FAA Advisory Circular 150/5390-2A recommends, in part, that the perimeter of private heliports be illuminated with yellow lights or floodlights. The approach path to the pad was over water, with rising terrain and 75-foot trees beyond the pad. The passenger stated that it was a very dark night. The FAA Aeronautical Information Manual indicates that an absence of ground features, as when landing over water, darkened areas can create the illusion that the aircraft is at a higher altitude than it actually is. According to the AIM, the pilot who does not recognize this illusion will fly a lower approach.