Cousin of British billionaire on the Titanic sub says OceanGate took 'far too long' to raise the alarm after it lost contact

• The cousin of a Titan submersible passenger said OceanGate took "far too long" to alert the coast guard.
• The US Coast Guard said it was told the vessel was overdue around eight hours after contact was lost.

The cousin of one of the passengers on the submersible that went missing when trying to reach the Titanic wreckage criticized its operator for not raising the alarm sooner.

Kathleen Cosnett, 69, a cousin of passenger Hamish Harding, told The Telegraph that OceanGate should not have waited eight hours to contact the Coast Guard.

"It's very frightening," she said.

"[It] took so long for them to get going to rescue [them], it's far too long. I would have thought three hours would be the bare minimum."

OceanGate did not immediately respond to Insider's request for comment.

The Titan submersible with five people on board lost contact with its mothership an hour and 45 minutes into its trip on Sunday, according to the US Coast Guard.

The Coast Guard said the submersible was launched at 8 a.m. on Sunday, but that it was told the submersible was overdue at 5.40 p.m. — around eight hours after the communications were lost.

A desperate search then began.

As of Thursday, it is not clear if the submersible is intact or if it has imploded. Rescuers say the vessel could be on the ocean floor or floating on the surface, meaning a large area to cover.

The search is a race against time, with the US Coast Guard saying it had 96 hours of oxygen for its journey.

That time passed on Thursday morning, but the search continued.

Some equipment that could be key to the search was only arriving or was still on its way to the site on Thursday.

Cosnett told The Telegraph is was "worrying" her cousin and the other passengers "may not have any extra oxygen left."

Harding is a noted explorer who has twice visited the South Pole. He flew to space last year on a Blue Origin craft, and holds a Guinness World Record for the longest time spent navigating the deepest part of the ocean, the Mariana Trench.

His godson, Robert Evans, told The Telegraph the family found out Harding was missing on Sunday night.

"He's been like a father to me. A second father you could say. We are all still remaining hopeful."

He said Harding "took me on adventures, skiing, scuba diving, and to Machu Picchu. He was just incredibly good to me."

The other passengers on board are 61-year-old OceanGate founder and CEO Stockton Rush, 77-year-old former French navy captain Paul Henry Nargeolet, 48-year-old British-Pakistani businessman Shahzada Dawood, and his 19-year-old son Suleman Dawood.