LAWYERS representing victims of the Clutha helicopter disaster said their clients are "desperate to know" why the aircraft crashed, as investigators prepare to hold the first of two private briefings with the bereaved families in Glasgow tomorrow night.

Senior members of the Air Accident Investigations Branch (AAIB) will reveal the details of the highly-anticipated report into the tragedy this week.

Relatives of those who died have been invited to attend one of two three-hour briefings at a Glasgow hotel, the first on Wednesday night and the second on Thursday morning.

The Herald: A police helicopter crashed into the Clutha Bar in Glasgow.

It is expected that their lawyers will also be allowed to attend, but the briefings are closed to the press and public.

It is also understood that some people who were seriously injured in the Clutha crash are furious after being left out of the briefings.

The full report is expected to be made public on Friday.

David Bell, a solicitor for specialist aviation law firm, Irwin Mitchell, which is representing 17 clients who were injured or lost loved ones, said they were hoping for clear answers on what caused the crash.

Mr Bell said: “All of those we represent have faced an incredibly difficult two years, waiting for any form of information on how this terrible incident came to occur.

“The effect of this wait cannot be underestimated, as many have simply been unable to move on or come to terms with the incident as a result of the long silence on this matter.

“We truly hope that this week will mark the end of this difficult period and help all of those affected to gain an understanding of what happening on that terrible evening.”

The police helicopter was returning from a routine operation on Friday November 29, 2013, when it appeared to "drop like a stone" onto the roof of the Clutha Vaults pub, causing it to cave in.

The Herald: Pilot Captain David Traill was among those who lost their life in the Clutha crashPilot Captain David Traill was among those who lost their life in the Clutha crash

The pilot and two police constables on board were killed. Another seven people inside the pub also died, and dozens were injured.

There was no mayday and nothing to indicate that the pilot had attempted an emergency landing.

An interim report in February 2014 said that both of the helicopter's engines had "flamed out" within seconds of one another after being starved of fuel, despite 76kg of fuel remaining in the main tank.

Investigators found that pumps which control the flow of fuel from the tanks to the engines had been switched off, when they should have been on throughout the flight.

The inquiry has also been complicated by the lack of a black box on board the aircraft, a Eurocopter EC135.

The Herald: Clutha owner Alan Crossan with First Minister Nicola Sturgeon. The pub re-opened in July following refurbishmentsClutha owner Alan Crossan with First Minister Nicola Sturgeon. The pub re-opened in July following refurbishments

Jim Morris, a former RAF pilot and partner in Irwin Mitchell’s Aviation Law team, said: “There are many questions which still need to be answered following the tragedy at the Clutha Vaults. The central question is what caused both engines of a modern helicopter to flame out?

“Many of our clients are desperate to know the answer to that question after a long and painful wait. Had the helicopter been fitted with the black box equipment, the answer to this crucial question may have been known and published by the AAIB at a much earlier stage.

“We hope that the meetings between the AAIB and the victims this week and the publication of the final accident report will identify the full chain of events that led to this tragedy. With the benefit of the AAIB's findings, we hope that the victims, the industry and the authorities will fully understand what went wrong and that steps will be taken to improve helicopter safety and prevent a similar tragedy in the future.”