Joe Cusker, 59, was inside the pub when the helicopter crashed through the roof on 29 November.
It is particularly difficult to design controllers for non-stationary maneuvers in which the helicopter goes through various flight regimes, extensively exposing the great complexity of helicopter dynamics.
Eyewitness: Lucky escapes Sharon Moore The voluntary worker, who has five children and who lives nearby, saw the helicopter slice through the crane "as if it was a piece of paper".
There had been a party atmosphere in the Clutha on Friday, with the ska band Esperanza in full swing, when, at about 10.25pm, the helicopter crashed through the roof on to the bar, filling the room with blinding, choking dust.
Throughout the day, a steady stream of people arrived at The Clutha pub in the city centre to lay floral tributes to those who died when the helicopter smashed through its roof.
After the helicopter swooped through a lush green valley and touched down, Goose, the founder of One, a UK-based philanthropic business that funds clean water programmes for communities in Malawi, said: "Tragic doesn't even come close.
Police took Mr Clegg, who was also accompanied by Glasgow City Council leader Gordon Matheson, inside the cordon to see where the helicopter came through the roof of the Clutha bar at 22 25 on Friday.
The helicopter broke through the clouds and rapidly dropped into the area where Hambleton was hidden.
Seconds later, the helicopter tore through the treetops and slammed into a house, killing his passenger, Charles Farmer, a 59-year-old co-worker.
"Before the storm this was all completely developed," Coyt Bailey, the helicopter pilot, said through his headset.
