A police helicopter similar to the one which crashed into the Clutha Vaults pub repeatedly gave false fuel readings.

An experienced pilot has said a cockpit display on his EC135 aircraft would show that the amount of fuel in its tanks rose after take-off.

Captain Andrew Mortimore told a Fatal Accident Inquiry (FAI) that one particular helicopter used by police in the English Midlands had sparked concern as far back as 2007.

The inquiry seeks to find out answers as to why Police Scotland helicopter G-SPAO crashed through the roof of the Clutha Vaults on November 29, 2013.

Ten people were killed - including three helicopter crew - and 31 people were injured.

READ MORE: Clutha Fatal Accident Inquiry: Lack of crash data 'frustrating'

The Clutha helicopter had five low fuel warnings before it crashed in Glasgow.

Former army pilot Mr Mortimore, 59, has clocked more than 4000 hours on an EC135, including one called GN-MID which flew out of Ripley, Derbyshire, North Midlands.

Mr Mortimore said that in the summer of 2007 he and colleagues noticed problems with the fuel gauge on GN-MID. Documents made at the time showed fuel indications could be out by as much as 40%.

Under questioning from Sean Smith QC, a Procurator Fiscal Depute, he said: “We were observing that nose-up attitudes reductions [on the gauge] and nose-down attitudes produced increases.”

A helicopter tends to cruise with its nose down and to hover with its nose up. This changes the level of liquid in its tanks, though on board computers should compensate for this.

Mr Mortimore described how he logged readings over 25 flights. He said: “You would expect a steady reductions in numbers. We would see the total fuel quantity increasing.”

READ MORE: Clutha tragedy could have been prevented, expert says

Mr Mortimore, now senior pilot at the HQ of the National Police Air Services, described some readings showing the aircraft had more fuel on board than it had had take-off.

He said manufacturers had been informed and that the problem did not re-occur until 2012. The same aircraft later gave questionable readings again in 2018. Minutes of a group of EC135 “users” from October 2007 were shown to the court. They read: “Errors reported by North Mids of up to 40% in fuel indications. Both fuel sensors found to be dirt contaminated...Members reminded that in the event of a red Low Fuel caption illuminating ....to land as soon as possible.”

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Earlier the inquiry heard manufacturers Airbus knew about issues with the EC135 model’s fuel readings a decade before the Clutha crash. It also earlier heard that the engineer who worked on the Clutha helicopter the day before its doomed final flight had warned an “accident is waiting to happen.”

Pilot David Traill, 51; PC Tony Collins, 43; and PC Kirsty Nelis, 36, died along with seven customers who were in the bar, Gary Arthur, 48; Joe Cusker, 59; Colin Gibson, 33; Robert Jenkins, 61; John McGarrigle, 58; Samuel McGhee, 56; and Mark O’Prey, 44.