Sad Details of Alaska Helicopter Crash Killing Five Passengers

The helicopter carrying Czech billionaire Petr Kellner, 56, just missed clearing an Alaskan ridge by three to five metres when it crashed, preliminary investigations show.

Mr Kellner, who is worth an estimated US$17.5 billion (A$23 billion) according to Forbes, was one of five passengers on board the fatal flight on Saturday (local time).

It's been reported the group was on a helicopter-skiing excursion north of Anchorage when the Airbus AS350 B3 slammed into a mountain and rolled hundreds of metres.

Mr Kellner, the richest man in the Czech Republic; Benjamin Larochaix, 50, from the Czech Republic; Gregory Harms, 52, of Colorado; and two Alaska residents - 38-year-old Sean McManamy, from Girdwood, and 33-year-old pilot Zachary Russel, from Anchorage - all died at the scene.

The survivor, identified as 48-year-old David Horvath from the Czech Republic, was listed in serious condition on Monday, Mike Canfield, a spokesman at Providence Alaska Medical Center in Anchorage, said.

Tragically, early investigations by the National Transportation Safety Board (NTSB) reveal the helicopter appears to have hit the mountain three metres to 4.57 metres below a mountain ridgeline.

It then rolled 244 to 274 metres downhill, NTSB member Thomas Chapman said during a recent briefing.

The helicopter was heard from on 6.34pm on Saturday and another aircraft found the wreckage about 9.30pm, Mr Chapman said.

The weather was noted as "relatively clear" when the helicopter was found, but Mr Chapman said "the area is very rugged, both in terms of terrain and in terms of weather conditions", according to Bloomberg.

Mr Chapman said the team investigating the crash would look at airworthiness, operations, meteorology, structures,...