Engineer who signed letter of concern about Titanic submersible says expedition advertising 'wasn't transparent enough'

An engineer who signed a letter sent to the company behind the doomed Titanic submersible several years ago says advertising about its expeditions wasn't transparent enough for people to know what they were getting into.

A recovery mission is underway for the passengers onboard the Titan, a submersible exploring the wreckage of the Titanic, after a debris field was found on the ocean floor following what the US Coast Guard described as a "catastrophic implosion".

Bart Kemper was one of the signatories of a letter drafted to OceanGate in 2018 from a group of experts warning the company its experimental approach could cause damage to the industry.

He told AM there were two major concerns he and other experts raised with OceanGate.

"The forward-facing website and advertisements about their activities were not transparent enough, in the view of many," Kemper said.

"It did not explicitly say, 'This is an experimental craft under experimental conditions.'

"The other aspect is the standard of care for design in engineering is, usually, you have codes and standards that give you the guidance of how to do the design, and then you have some sort of jurisdictional authority - in this case, a marine classing society - that would provide the oversight for testing, design review and be that objective third party to ask the hard questions and check that design."

Kemper wasn't the only expert to raise concerns about the Titan. That same year, David Lochridge, an OceanGate worker, sent the company's leaders an engineering report he wrote blasting its research and development process for the Titan, according to a lawsuit.

"The paying passengers would not be aware, and would not be informed, of this experimental design, the lack of non-destructive testing of the hull or that hazardous flammable materials were being used within the submersible," the lawsuit said.

"Rather than address his concerns or undergo corrective action to rectify and ensure the safety of the experimental Titan, or utilise a standard classification agency to inspect the Titan, OceanGate did the exact opposite - they immediately fired Lochridge. OceanGate gave Lochridge approximately 10 minutes to immediately clear out his desk and exit the premises."

Lochridge's legal action was a countersuit against OceanGate after his former company alleged he'd talked about confidential business details with two people before his sacking.

Following the discovery of the vessel debris, US Coast Guard Rear Admiral John Mauger said it was too early to tell exactly when the Titan became doomed.

OceanGate was the first to confirm the news on Friday morning (NZ time) all five people onboard had died.

That was followed by a detailed press conference, where the Coast Guard revealed debris belonging to the Titan on the seafloor had been found near the site of the Titanic wreck.