PILOT error was not to blame for the Clutha helicopter crash, it is understood an interim report into the disaster will reveal.
Preliminary findings on the tragedy point the finger at faulty fuel gauges aboard the police helicopter as the likely source of the accident.
Three crew members and seven people on a night out died when the Eurocopter EC135, operated by Bond on behalf of Police Scotland, plummeted onto the roof of the Clutha Vaults pub in Glasgow on the night of November 29, 2013.
It had been returning from a routine operation when, according to eyewitnesses, it "dropped like a stone".
The report goes some way to explaining why two vital fuel switches came to be turned off shortly before the crash.
It also sheds light on a worldwide safety alert issued by Eurocopter to operators of the same model that crashed in Glasgow, saying that a problem with the low fuel level warning system had been discovered in a number of aircraft.
The warning, issued in December less than two weeks after the crash, came after an air ambulance, one of its 22 aircraft leased in the UK, was found to have a fuel indicator problem. Tests found others also had the same fault.
The initial investigation by the the Air Accidents Investigation Branch (AAIB) found that the Eurocopter EC135 suffered double engine failure as a result of fuel starvation.
The aircraft had 76kg of fuel in its main tank but none of the fuel was reaching the engines because the key transfer pumps had been switched off.
As a result fuel could not transfer from the main tank into the two supply tanks, which in turn pump fuel to the left and right engines.
The switches which control the pumps are located in the cockpit ceiling to the rear of the pilot and can only be turned off manually.
The fact that fuel switches were turned to the off position was previously said to be the "smoking gun" behind the tragedy, as they control the flow of fuel to the engines and were both supposed to be on throughout flight.
It suggests that the pilot may have been trying to reset the system after being tricked into thinking there was a problem with the fuel supply.
The AAIB report on February 14 stated that there was zero fuel in the right supply tank and just 400g in the left supply tank at the time of impact.
It noted that "in the latter stages of the flight, the right engine flamed out, and shortly after the left engine flamed out". A series of low-fuel warnings were also recorded during the flight.
Along with pilot David Traill, PC Tony Collins and PC Kirsty Nelis were on board the helicopter and were killed in the crash.
The seven customers in the Clutha who lost their lives in the accident were John McGarrigle, Mark O'Prey, Gary Arthur, Colin Gibson, Robert Jenkins, Samuel McGhee and Joe Cusker.
A spokesman for the Air Accidents Investigation Branch, which issued the interim report, said: "This report is not the final report and we will not be commenting at this stage."
Why are you making commenting on The Herald only available to subscribers?
It should have been a safe space for informed debate, somewhere for readers to discuss issues around the biggest stories of the day, but all too often the below the line comments on most websites have become bogged down by off-topic discussions and abuse.
heraldscotland.com is tackling this problem by allowing only subscribers to comment.
We are doing this to improve the experience for our loyal readers and we believe it will reduce the ability of trolls and troublemakers, who occasionally find their way onto our site, to abuse our journalists and readers. We also hope it will help the comments section fulfil its promise as a part of Scotland's conversation with itself.
We are lucky at The Herald. We are read by an informed, educated readership who can add their knowledge and insights to our stories.
That is invaluable.
We are making the subscriber-only change to support our valued readers, who tell us they don't want the site cluttered up with irrelevant comments, untruths and abuse.
In the past, the journalist’s job was to collect and distribute information to the audience. Technology means that readers can shape a discussion. We look forward to hearing from you on heraldscotland.com
Comments & Moderation
Readers’ comments: You are personally liable for the content of any comments you upload to this website, so please act responsibly. We do not pre-moderate or monitor readers’ comments appearing on our websites, but we do post-moderate in response to complaints we receive or otherwise when a potential problem comes to our attention. You can make a complaint by using the ‘report this post’ link . We may then apply our discretion under the user terms to amend or delete comments.
Post moderation is undertaken full-time 9am-6pm on weekdays, and on a part-time basis outwith those hours.
Read the rules hereComments are closed on this article