The families of the RAF Chinook crash victims have asked the court to allow the case to continue.

CJC lawyers told the High Court on Tuesday that the information about the Chinook’s airworthiness “raises a more than arguable claim … that the individuals who died in the crash were on board an unsafe aircraft”.

He added that there were “deep and clear” concerns about airworthiness, but that despite several investigations into the crash, no investigation had ever looked into the matter.

Sam Jacobs, for the CJC, told the court in London: “It is historic that the families of the 29 casualties still have unanswered questions, but they still face unanswered questions in what has been called the RAF’s worst peacetime disaster.”

Several relatives of the deceased attended court and some wept during the hearing.

Andy Tobias, whose father, Lieutenant-Colonel John Tobias MBA, died in the crash, called the day a “huge milestone”.

The helicopter was carrying 25 intelligence officers and four special forces personnel from RAF Aldergrove in Northern Ireland to Fort George in Northern Ireland when it crashed in foggy weather.

In a written statement, Jacobs said the crash occurred two days after the helicopter arrived, following “much refinement and promotion.”

The corporation then sued Boeing for its modifications before the crash, and said the safety-critical engine control system on the helicopter had “deficient density” at the Aircraft and Weapons Test Facility.

Jacobs said the helicopter involved in the crash had needed its engine replaced three times in the months leading up to the accident.

“It is clearly arguable that airworthiness was the cause of the accident. Indeed, the HC-2 should not have been flown,” he said.

In a written submission to the MoD, Daniel Beard Casey said the crash was the subject of “extensive investigations” and the CJC “did not raise any material that would have revived any arguable duty to investigate”.

He also said Boeing’s litigation had “nothing to do with the accident” and that the CJC’s case was based on “clear assertions” about the helicopter’s airworthiness, without explaining why legal counsel had not filed sooner.

He added, “The evidence is sparse and time has passed so that no further meaningful investigation is possible or further investigation serves practical purposes.”

He continued: “The claimant essentially wants to bring the facts to light.

“However, that ambition must be seen in the light of the practical limitations, the civil questions that have been resolved, the lessons learned and the changed operational context.”

The hearing will conclude later on Tuesday.