The father of a man killed in the Clutha helicopter tragedy in Glasgow has criticised air accident investigators' ''cack-handed'' response to the crash.
Ian O'Prey, whose son Mark was among 10 people killed in the crash, has questioned why the Air Accidents Investigation Branch (AAIB) does not have the power to enforce its recommendations.
The AAIB has recommended the Civil Aviation Authority (CAA) "requires" all police helicopters to be "equipped with a recording capability that captures data, audio and images in crash survivable memory".
But Mr O'Prey said a similar recommendation in the past has not been acted upon.
Following a fatal air ambulance crash in July 1998, the AAIB recommended the CAA should "encourage the development" of lightweight and low-cost flight recorders, and "consider" whether they should be used in emergency service helicopters.
The report also concluded the pilot did not follow emergency procedures after a fuel warning in the cockpit.
Investigators found that two fuel supply switches were off, yet the helicopter continued to carry out three surveillance jobs over nearby Lanarkshire rather than land on the night of the crash on November 29 2013.
Mr O'Prey told the Press Association: "They just said the switches were off, but they don't know why they were off and they would never know why they were off.
"They didn't apportion any blame at all and I don't want to go down that road because the pilot's family have to listen to all the nonsense that is being said.
"I don't have any proof, but I think it was a machine malfunction. I know from household electrical equipment that switches can just trip, so maybe that's a possibility.
"The AAIB can only make recommendations. What is the point in that?
"They've recommended flight data recorders be installed before, but there's still aircraft flying around without them, so what good has it done? It's a bit of a cack-handed effort, to be honest."
More than 100 people were enjoying a night out at the Clutha pub when the helicopter crashed through the roof as it was returning to its base on the banks of the River Clyde in Glasgow.
Chief inspector of air accidents Keith Conradi said the AAIB was "deeply frustrated that we had only a limited evidence set to work on for this accident, and it hasn't given us all the answers".
He told BBC Radio 4's World at One that flight recorders would have given more information about how the aircraft was being flown.
"Perhaps most crucially of all the cockpit voice recorder would have told us how the pilot and the two police observers reacted when the fuel low level warning light came on," he said.
The pilot, David Traill, who was attached to Police Scotland's air support unit, was a highly experienced former RAF and training pilot with more than 5,500 flying hours in helicopters.
The AAIB found that the helicopter's low fuel warnings were triggered and acknowledged five times during the flight.
Investigators added that the pilot did not complete the emergency shutdown checklist following the first engine failure. The second engine failed 32 seconds later.
Director of operations for the National Police Air Service (NPAS), Ollie Dismore, said: "We are fully supportive of the recommendations in today's report which include fitting black box recording equipment to all police helicopters.
"NPAS will work with the CAA to fully implement all the new safety regulations."
The CAA issued a statement which said it assisted the AAIB with its investigation and was "studying the report and its recommendations".
Jim Morris, a former RAF pilot and specialist aviation lawyer at Irwin Mitchell, which represents 17 people affected by the crash, said there is a clear need for flight data recorders on helicopters.
"The crucial real-time evidence from a flight data recorder and cockpit voice recorder would have enabled the investigators to reconstruct in far more detail what the pilot and helicopter were actually experiencing and the sequence/ timing/reasons for the events that occurred," he said.
"Our focus is on ensuring those who lost loved ones in the crash and those who suffered injuries get the help and support they still need at this most difficult time.
"It has been a tough week for the Clutha crash victims and those we have spoken to generally feel incredibly disappointed that they may never know exactly what went wrong."
Aviation safety expert David Learmount claimed police forces have not previously used flight recorders in every helicopter because "they are expensive".
He explained: "It's just budget. That is all it's about because they could have put things on board."
Mr Learmount, who is consulting editor of Flightglobal magazine, said technology has developed so devices to record flight information can be made small enough for use on helicopters.
"With big airliners you can put on a large heavy box, but a helicopter is lightweight and hasn't got much space," he said.
"A number of years ago miniaturised, clever pieces of electronics were difficult to design and expensive, but they're less so now.
"(The AAIB) can make recommendations for things that would not have been practical previously."
Those who were in the helicopter - the pilot and police constables Tony Collins and Kirsty Nelis - were killed when the helicopter crashed into the building.
As well as Mr O'Prey those inside the pub who were killed were John McGarrigle, Gary Arthur, Colin Gibson, Robert Jenkins, Samuel McGhee and Joe Cusker.