Marcus Cook, a senior inspector with the Air Accident Investigation Branch (AAIB), told a fatal accident inquiry that the pilot, David Traill, received a total of five low fuel warnings that were triggered automatically in the cockpit of his aircraft.
Mr Cook said every time a fuel warning illuminated on helicopter dashboard, it would be accompanied by an “audio gong” which would have been heard by anyone on board.
G-SPAO, the registered name of the EC135 helicopter involved, crashed on the roof of the Clutha bar in Glasgow city centre on the evening of November 29, 2013, killing the three people on board as well as seven customers in the building.
The second day of the inquiry heard that Mr Traill had been instructed on the specifics of the EC135 helicopter’s fuel system during training in 2008. This included a requirement to land within 10 minutes of being presented with a low fuel warning.
The court also heard an excerpt from the final AAIB report into the crash. It noted at the time of the accident in 2013, the EC135 model had accumulated more than three million flying hours over 20 years.
It added: “There had not previously been a reported instance of fuel starvation.”
The report, published in 2015, found two fuel supply switches were off and the pilot did not follow emergency procedures after a fuel warning in the cockpit.
The Crown Office has previously said there is insufficient evidence for criminal proceedings.
Mr Cook also told how a Caution and Advisory Display (CAD) would have been functioning at the time.
This should have shown how much fuel was in the main tank, the left supply tank and the right supply tank.
There had been intermittent warnings recorded but they do not reveal when they were triggered.
Mr Cook said: “The low-fuel warning remained on for the remainder of the flight.”
The FAI before Sheriff Principal Craig Turnbull is taking place in a temporary court at Hampden Park in Glasgow.
It also heard there are no plans to reopen the AAIB investigation into the crash.
Phil Sleight, deputy chief inspector of air accidents, told the inquiry there had been new documents presented but none of them were considered new or significant enough.
The purpose of the FAI is to determine the cause of the deaths, establish whether they could have been prevented and enable the sheriff to make recommendations that could prevent fatalities in similar circumstances.
More than 100 people were at the Clutha bar when the helicopter, returning to its base on the banks of the River Clyde, crashed through the roof.
A total of 57 Crown witnesses are expected to give evidence at the inquiry, down from a previous estimate of 85.
Police have taken more than 2,000 statements as part of preparations for the FAI, while the Crown has around 1,400 productions.
The inquiry is expected to involve around three months of evidence spread over six calendar months this year.