The spouses of the two police officers who died when their helicopter crashed into the Clutha bar in Glasgow six years ago have made public their “deep concerns and frustrations” with the findings of a fatal accident inquiry which blamed the crash on pilot error.

The crash on the night of Friday 29 November 2013, killed the pilot, CaptDavid Traill, and police constables Tony Collins and Kirsty Nelis, along with seven customers of the bar, injuring 31 more. Last month, a fatal accident inquiry concluded that Traill had decided to ignore low fuel warnings.

But, in a joint statement released with the widow of Tony Collins, Mark Nelis insisted his wife trusted Traill “implicitly”. He also called on the Air Accident Investigation Branch (AAIB) to produce a fresh report into the crash, and to release amendments made to a previous report which he suggests may have been prompted by the helicopter’s manufacturer.

The statements echo strong criticism of the inquiry’s findings made by Traill’s fiancee, Lucy Thomas, earlier this month.

Thomas claimed the sheriff downplayed evidence indicating the manufacturer and aircraft were at fault and said there was clear evidence about the helicopter’s record of faults and errors in its maintenance manuals.

In his written determination after five months of oral evidence in a fatal accident inquiry, the sheriff principal, Craig Turnbull, said: “Capt Traill consciously took a risk in proceeding on the basis that the low fuel warnings were in some way erroneous (when they were not). That decision had fatal consequences.”

But Mark Nelis said his family was “deeply concerned and frustrated” with Turnbull’s findings and the AAIB, which published its report in 2015.

Referring to Turnbull’s conclusion that the pilot made a “conscious decision” to ignore the fuel warnings, he said: “We find these conclusions surprising given the surrounding evidence that the aircraft had numerous fuel reading issues prior to the incident and that a number of design changes have been made to this aircraft type since.”

Nelis added: “We also have deep concerns with regards to the AAIB whom we believe should provide a fresh independent report in light of this determination as well as releasing all forms of its report as it developed.

“The first draft report issued by the AAIB was sent to interested parties, including the helicopter owners and manufacturers, prior to its publication. The report was finally released over four months late and had been amended on a number of key points. We have not been made aware of why it was changed or what contributions were made to it.”

Lucy Collins said her husband “trusted and respected Dave Traill as a pilot, colleague and friend”.

She added: “He trusted Dave implicitly as the hugely experienced and skilled pilot he was. I feel this is important information that Tony would have wanted me to share. I felt very strongly that I wanted all those involved in the inquiry to know that Tony had trust and confidence in Dave Traill.”

An AAIB spokesperson said it stood by its final report and had no further comment.

A spokesperson at the Judicial Office for Scotland said: “In reaching its determination, the court has careful regard to all the material placed before the fatal accident inquiry.”