A TEST pilot has said he cannot imagine why an experienced pilot would not follow emergency procedures.

Rene Nater, a test pilot with Airbus in Germany, gave evidence at the Clutha Fatal Accident Inquiry (FAI).

He flew two flight tests to chart the final flight of helicopter G-SPAO, which crashed through the roof of the Clutha Vaults in November 2013.

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 previously heard that following five low fuel warnings, the right engine flamed out, followed just 32 seconds later by the left engine.

Read more: Test pilot tells inquiry of final flight of doomed Glasgow helicopter

The aircraft had just 10 seconds to fall before crashing through the roof of the Clutha bar.

The solicitor for the family of victim Gary Arthur asked Mr Nater: "If you as a pilot knew you had 32 seconds before the left engine would flame out, what could you do?"

Mr Nater said: "The element of surprise is playing a part if you lose the first engine in a situation like this where you have not taken any action to avoid it the surprise, well, you need at least two or three seconds before you realise what's happened."

Mr Nater went on to use a model helicopter to demonstrate to the court how a pilot would carry out a "very difficult" autorotation manoeuvre to attempt to land safely.

Read more: Fuel theories of helicopter's final flight heard

This would be, the court heard, particularly difficult at night with low visibility over "hostile terrain" such as a city with the pilot looking for an open space to put down.

Mr Nater was a pilot in the Royal Netherlands Air Force for 17 years and retired with the rank of major. The court heard he had also trained with the Royal Air Force.

Donald Findlay, acting for the family of Robert Jenkins, said: "It appears that somewhere between 900 to 1000 feet Alpha Oscar [the helicopter] lost one engine.

"Are you telling us that from that point on the flight was doomed?"

Mr Nater said: "If you have fuel starvation with both engines you are doomed unless you have an open area in front of you [to land]."

Read more: German aeronautical engineer to give evidence

Mr Findlay questioned Mr Nater about the fact the G-SPAO helicopter's fuel pumps were switched off.

He said: "What is troubling me and is troubling other people, is that we have pumps which are switched off that don't need to be switched off and this helicopter crashed and people died.

"I am trying to find out why it would be you would switch off the fuel pumps."

Mr Findlay asked the pilot what he would do if he faced a low fuel warning, such as the five low fuel warning pilot David Traill was known to have had in the Clutha helicopter.

Mr Nater replied that he would start a stop watch as it vital to land within "eight to 10 minutes", and put the fuel pumps back on.

Mr Findlay said: "Is that a practice of yours?"

The pilot replied: "Yes."

Read more: Chief inspector denies low fuel warnings were ignored

The QC said: "It that what you would train other pilots to do?"

Mr Nater said: "Yes sir."

Mr Findlay said: "Is that what you would expect another pilot to do?"

Mr Nater said: "Yes sir."

Mr Findlay asked if there were any circumstances under which a pilot would omit to do any of these things to which Mr Nater replied only if a more gravely seriously issue was happening in the cockpit, such as a fire.

Mr Nater added: "But I cannot say why in this case. I would be making assumptions and I really don't know.

"I get nervous when I see red lights. I think most pilots get nervous and I can only think that you would not react only if you were used to seeing them."

Under questioning from Shelagh McCall QC, counsel for Lucy Thomas, the fiancee of Mr Traill, Mr Nater explained more about autorotation.

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He said that pilots would learn the technique in a real helicopter, rather than a simulator, as it is hard to accurately simulate the "critical time" of the final moments of the technique when the aircraft is 60 feet from the ground.

However, Ms McCall turned to a manual that said the opposite is the case and suggested that someone who had only practised in a simulator would be at a disadvantage in an emergency situation.

The inquiry before Sheriff Principal Craig Turnbull continues on Monday.