OPERATORS of the police helicopter that crashed into the Clutha Vaults pub in Glasgow has switched to a new computer system that avoids relying on pilots to self-report when aircraft have seriously low fuel issues.

The change was confirmed by Alexander Stobo, 44, now director of operations for Babcock Critical Services, who was head of flight operations for the helicopter operators Bond Air Services when Police Scotland helicopter G-SPAO crashed through the roof of the Clutha on November 29, 2013, killing ten - including three helicopter crew - and injuring 31.

At the time of the accident, Bond were relying on pilots to carry out mandatory self-reporting when fuel levels reached very low levels, the fatal accident inquiry heard.

But Mr Stobo, who joined Bond as an air ambulance pilot, said that a helicopter data monitoring system had  been introduced since the crash which meant they did not have to rely self-reporting.

Under cross-examination by Donald Findlay QC for the family of victim Robert Jenkins, Mr Stobo agreed that after the system was installed and pilots were under a mandatory obligation to report low final reserve fuel levels which were raised to 90kg, there had been two problem incidents reported.

Mr Stobo, who became Bond's head of flight operations seven months before the Clutha tragedy, said he could not recall whether any pilots had self reported fuel issues before the helicopter crash.

An Air Accident Investigation Branch probe found that pilot David Traill, 51, who died in the crash, did not follow emergency protocol and flew on despite low fuel warnings.

The fatal accident inquiry which entered its 14th day at Hampden earlier heard that Mr Traill had carried out an operator proficencies check which found that "all emergencies were completed to a very high standard".

The inquiry also heard again that the police helicopter should have put out a mayday call during its final journey.

According to guidance, the aircraft should also have had at least 85kg of fuel on board.

And the court heard if it went below that level then Captain David Traill should have issued the emergency signal.

The inquiry was previously told Air Accident Investigation Branch senior inspector Marcus Cook that the pilot would have been expected to make a PAN call - which would have indicated he had a fuel issue - "long before the final stages of the flight".

It heard that five separate low fuel warnings would have gone off in the doomed Eurocopter EC135 helicopter which crashed into the pub and some of the warnings would have been made intermittently.

When Mr Traill (below) was returning to the Clyde heliport from Bothwell, the helicopter was estimated to have 86kg of fuel on board. At the time of the crash the helicopter was said to have had 76kg of fuel on board.

HeraldScotland:

Mr Findlay asked Mr Stobo if an EC135 had landed with less than 60kg of fuel, whether he would have expected that to be reported to him either as head of flight operations or as director of operations.

"After the accident the policy was changed to 90kg and if someone then landed below the 90kg final reserve, it was reported appropriately," said Mr Stobo.

"How many times was it reported to you in either capacity," asked Mr Findlay.

"I don't recall any up to the accident, but I do recall two incidents after it happened," said Mr Stobo.

"Was it self reported or throught the computer system," quizzed Mr Findlay.

"I don't recall," said Mr Stobo.

Asked if before the crash, pilots would generally adhere to the reporting policy over admissible fuel levels , Mr Stobo said: "I can't say. Unless it was reported to me I would not be aware of it." Mr Stobo said that a PAN alert call should have been made when a pilot was going to utilise reserve fuel.

HeraldScotland:

Mr Findlay asked: "On the face of it we have a pilot who is flying along, ignoring warnings and then lands, if he had landed the aircraft, below admissible levels. What might be going on in someone's head at this point in time." Mr Stobo said: "I can't assume without further evidence of what is going on, what the circumstances were that he was looking at.

"It is important in the aviation environment that any lessons learnt are published, and collectively grown from, so we encourage reporting with every event so we can all learn. An investigation would determine the circumstances that would have led to that decision." An AAIB special report found both engines “flamed out" in the doomed helicopter.

One of the fuel tanks was empty, while a second contained 0.4 litres. A third contained 75 litres, but transfer pumps to take this fuel to the other two engine tanks were switched off.

The probe also found fuel transfer pumps were turned off and a controlled landing was not achieved for “unknown reasons”.

And it recommended all police helicopters be equipped with black box flight recording equipment.

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.

The inquiry before Principal Sheriff Craig Turnbull continues.