Robinson Helicopter Company R44 N4138M accident near Solomon, Alaska

Probable cause

The pilot's failure to maintain adequate altitude above water, and his loss of situational awareness, which resulted in an inadvertent descent and collision with water.

NTSB analysis

The pilot was conducting a commercial charter flight for the passenger to place mineral claim markers. He stated that, while flying over a lagoon at an altitude lower than he "should have been," while making inputs to the GPS unit, he likely inadvertently applied forward cyclic and allowed the helicopter to descend into the water below. The pilot reported that there were no mechanical malfunctions or anomalies with the helicopter that would have precluded normal operation.

Although helicopters operated under 14 CFR Part 135 are required to be equipped with radar altimeters, the accident helicopter was not, as the operator had been authorized by the Federal Aviation Administration (FAA) to operate the helicopter without one. It is likely that if a radar altimeter was installed in the helicopter at the time of the accident, was functioning properly, and was set to provide an aural warning at a predetermined altitude, the pilot may have had adequate time to recognize and stop the inadvertent descent before impact with water.

Text from the NTSB. Open the NTSB docket for ANC17LA040 for the full record.