ANCHORAGE, Alaska (AP) — The family of a Czech billionaire who died in a heli-skiing crash in Alaska in 2021 says in a lawsuit that he survived the impact but succumbed to his injuries in the hours between the crash and when rescue personnel arrived.

The lawsuit, filed in Alaska state court recently on behalf of the family of Petr Kellner, alleges negligence and seeks punitive and other damages. Kellner, at the time of his death, was the richest man in the Czech Republic. The lawsuit names as defendants Soloy Helicopters; Triumvirate LLC, which owns and operates Tordrillo Mountain Lodge; and Third Edge Alaska LLC, which was doing business as a heli-ski guide service but administratively dissolved last year.

Five people died in the crash in the Chugach Mountains 21 miles (34 kilometers) southeast of Palmer in one of the deadliest heli-skiing aviation accidents in North America, the Anchorage Daily News reported.

The sole survivor, Czech snowboarder David Horvath, is separately suing the lodge over injuries he suffered. Palmer is about 45 miles (72 kilometers) north of Anchorage. Horvath’s attorney, Tracey Knutson, said Kellner and a guide lived through the impact but died before rescuers arrived.

A final crash report from the National Transportation Safety Board is expected later this year, the agency’s Alaska chief said.

A Soloy representative declined comment to the newspaper. Triumvirate, in a statement, declined to comment on the litigation.

“Triumvirate LLC and its employees again express condolences to the families who lost loved ones and to the survivor who was injured in the helicopter crash,” the statement said. “To be clear, Triumvirate LLC was not responsible for the crash and there is no merit to the claims against Triumvirate LLC.”

Kellner was seriously injured but alive and conscious after the crash, according to the wrongful death lawsuit filed on behalf of his family. The lawsuit does not provide details on the nature of his injuries or his cause of death.

The companies should have known about the crash immediately and notified authorities but failed to monitor the location of the helicopter and failed to maintain contact with the pilot and guide, the lawsuit alleges. An emergency location transmitter installed in the helicopter did not activate on impact, the lawsuit states.

The men originally planned to stay at a lodge property near Skwentna but a COVID-19 case prompted them to stay at a home on Wasilla Lake instead.

Horvath, trapped in his seat after suffering broken ribs and dislocated knees, wasn’t extricated for nearly six hours, according to his attorney, and lost all the fingers on his left hand and some on his right to frostbite.