LAX99FA137 · Mbb B0-105CBS-4 B0-105CBS-

The medical evacuation helicopter was on a positioning flight back to its remote base location on a dark night. The pilot received a weather briefing at 1700; however, there was no record of him receiving an update. The area forecast was for broken clouds, scattered light rain showers, instrument flight rules (IFR) conditions, strong northerly winds over rough terrain, light to occasional moderate rime icing in precipitation, and a freezing level between 7,000 and 9,000 feet mean sea level. A winter advisory was in effect for 2 to 3 inches of snow with winds from the southeast at 13 to 22 knots. A motorist saw the helicopter flying west over a highway leading to the accident site at 1,000 feet above ground level (AGL). The sky was overcast with freezing rain that turned into wet snow and then finally freezing sleet. A second motorist nearer the accident site saw the helicopter using its searchlight to follow the highway at 150 to 200 feet AGL in conditions of lower clouds and reduced visibility. A resident next to the accident site heard the helicopter flying back and forth for a few minutes followed by the crash. He drove in the direction of the sound and found the crash site in flames. Snow had reduced visibility to less than 50 yards at the time. The aircraft was not certified for flight in IFR conditions; however, it had full flight instruments, a radar altimeter, a GPS, and VHF navigational radios. The operator reported the pilot had undergone an inadvertent instrument meteorological conditions evaluation within the last 90 days; however, documentation of this training was not found.

Verbatim NTSB analysis and probable cause from the NTSB dataset