A submarine pilot hired to assess the now-missing Titanic submersible warned in 2018 that its hull monitoring system would only detect failure "often milliseconds before an implosion."
David Lochridge, a submarine pilot and inspector from Scotland, said in court filings that he was fired after expressing concerns about the safety of the Titan - a 22-foot submersible that disappeared on Sunday while carrying five people to see the wreck of the Titanic.
Lochridge was hired by OceanGate, the Washington-based company that runs tours with the Titan, as director of marine operations and started working with the firm in 2015, per the court filings seen by Insider.
He was accused by OceanGate of violating a nondisclosure agreement in 2018, but countersued the firm and said he was fired after becoming a whistleblower.
Lochridge was asked in January 2018 to inspect the Titan, according to his counterclaim. At the time, the vessel ws not yet being used in deep-sea tours.
Lochridge said he raised "serious safety concerns" in his inspection report, including issues regarding the viewport's design. His primary worry, however, was over a lack of testing on the Titan's hull, Lochridge said in his countersuit.
OceanGate was relying on an "acoustic monitoring system" that would detect when the hull breaks down, Lochridge said in his lawsuit.
But Lochridge warned that the system would "only show when a component is about to fail - often milliseconds before an implosion," and couldn't detect if any existing flaws were already affecting the hull, the lawsuit said.
"Non-destructive testing was critical to detect such potentially existing flaws in order to ensure a solid and safe product for the safety of the passengers and crew," Lochridge's lawsuit said.
However, the submarine pilot said OceanGate told him that the Titan's hull was too thick to scan for weak spots and adhesion issues.
Lochridge said that after he submitted his inspection report, OceanGate fired him and gave the pilot "approximately 10 minutes to immediately clear out his desk and exit the premises."
A representative for OceanGate told Insider that the firm is unable to provide comment on Lochridge's lawsuit.
It's unclear if the pilot's concerns were ever addressed or whether OceanGate later ran the tests he recommended. Lochridge's case was settled out of court in November 2018.
Three years after the lawsuit, OceanGate launched annual tours to see the sunken Titanic. On its third expedition, the Titan lost contact with its mother ship on early Sunday afternoon as it was more than an hour into its journey to the Titanic.
Five people were inside the submersible - OceanGate CEO Stockton Rush, British adventurer Hamish Harding, French explorer and diver Paul-Henry Nargeolet, and Pakistani-British philanthropist Shahzada Dawood and his son, Suleman.
The US and Canada have launched a massive search and rescue operation, and it's not immediately clear what happened to the submersible. But there are fears that the vessel's hull may have been breached, which at such depths would spell certain death for all the passengers.
If the Titan's hull is still intact, its passengers have oxygen to last at most until Thursday afternoon, Eastern Time, per the US Coast Guard.
Lochridge wasn't the only one to raise safety issues for the Titan.
The New York Times on Tuesday published a 2018 letter to Rush from the Marine Technology Society, which expressed "unanimous concern" about the safety of OceanGate's "experimental approach" with the submersible.