text: Air accident investigators have been briefing families ahead of official publication of their final report.
  The police helicopter crashed onto the busy Clutha bar on 29 November 2013.
  An earlier interim report said the engines had shut down even though there was fuel in the reserve tank.
  Some relatives said the briefing had left many questions unanswered, and underlined the need for black box flight recorders to be fitted in all passenger-carrying aircraft.
  Following the meeting with the Air Accidents Investigation Branch (AAIB) in Glasgow on Wednesday evening, Ian O'Prey whose son Mark died in the bar, said there was "no resolution" to the tragedy.
  Mr O'Prey said there had been a few "heated moments" during the meeting but it "all calmed down".
  He said: "I don't think I'm any further forward. The AAIB - they think it was switches that were left on - or weren't left on.
  "My main question to them was flight recorders -  if they had flight recorders, it would have taken us a fraction of the time it has taken us.
  "Personally I feel calmer than I did before I went in. I can't keep shouting at the moon for the rest of my life although I feel I want to."
  Investigators are due to hold another closed meeting with bereaved relatives on Thursday and have asked families not to discuss the detailed findings until the report's official publication on Friday.
  John McGarrigle, whose father John died, said he felt "let down" despite optimism ahead of AAIB meeting.
  Mr McGarrigle said: "All tonight has done for me is raise loads more questions. My head is scrambled, I'm that angry.
  "Flight data recorders should be installed in every passenger-carrying aircraft - simple as. If we had that, we would know a lot more.
  "We wouldn't know the full cause, but we would know half of the reasons at least and we would have learned from it."
  Jim Morris, an aviation law expert with Irwin Mitchell Solicitors, also said the lack of a "black box" had hampered the investigation.
  He said: "Unfortunately, in my view, due to a lack of a requirement to fit a black box flight data recorder, we have almost more unanswered questions."
  Mr Morris added: "We still do not know why fuel did not reach the engines.
  "The report goes into significant detail in its analysis but it is clear from what is said in the report that they can't answer all the questions."
  Anne-Marie Kennedy, who was working behind the bar and was trapped in the wreckage, said she was "satisfied" with how the briefing went.
  She said: "It's shown me that they should have black boxes for defo, it's shown me the need for other regulation, but other than that nothing.
  "Until I speak to my legal team I can only speculate.
  "I'm satisfied with the way the night went. I believe that the AAIB has done everything in their power.
  "The guy explained the investigation, the complexity and the length of time. They did all they could."
  Find out more
  The Police Scotland Eurocopter EC 135, operated by Bond Air Services, came down on to the roof of the Clutha Bar at about 22:25 on a busy Friday night.
  The helicopter crew who were killed were pilot David Traill, PC Tony Collins and PC Kirsty Nelis.
  The seven customers in the Clutha who died were John McGarrigle, Mark O'Prey, Gary Arthur, Colin Gibson, Robert Jenkins, Samuel McGhee and Joe Cusker.
  The Air Accidents Investigation Branch (AAIB) issued an interim report last year which said that both engines on the helicopter "flamed out" due to a fuel supply problem.
  The report, however, did not set out the cause.
target: Relatives of the 10 people who died in the Clutha helicopter tragedy in Glasgow have been told fuel switches were in the off position when they should have been on.