David Miller, deputy chief inspector of the Air Accidents Investigation Branch (AAIB), said the helicopter made a vertical descent into the Clutha bar in Glasgow and the pilot made no mayday call.
He said: "I can confirm that the helicopter does not have a flight data recorder, however it does have a significant number of modern electronic systems on board and it may be possible to recover recorded data from those systems. There were no emergency transmissions from the pilot before this accident."
Nothing detached from the craft in flight before the accident, he said.
There is nothing to connect the incident with any previous accidents in the North Sea, he added.
The wreckage will be taken to the AAIB base in Farnborough, Hampshire.
Mr Miller described the recovery operation as "hazardous and very, very challenging".
He said: "The AAIB need to record and preserve the evidence but we are very mindful of the sensitivities that have surrounded the recovery of the bodies of those who have been fatally injured.
"While waiting for the wreckage to be recovered we have been looking at other aspects of this accident.
"We have the recorded radar data, so we know the track of the helicopter. That also tells us the height and speed of the helicopter in the latter stages of its flight.
"We have recorded radio information and transmissions.
"As far as the helicopter is concerned the systems do hold microchips that hold non-volatile memory in them and it may be possible to download that information from things such as the full authority digital electronic control systems that manage the engines.
"I can confirm that nothing detached from the helicopter in flight before the accident and that all four rotor blades were attached to the rotor head after the impact.
"I can also confirm that there's no cause to connect this accident with any previous accidents to helicopters operating in the North Sea environment."
The AAIB will issue a preliminary report "very soon", he said.
Police Scotland has said that the helicopter, a Eurocopter EC135 Type 2, was tested on the advice of its operator Bond Air Services last July.
It happened after Scotland's two air ambulance helicopters were suspended following a warning about their safety.
Eurocopter, the helicopter manufacturer, issued a safety information notice about its EC135 fleet early last May after reports of cracks on the machines.
The company issued the notice after it was given reports about cracks on the lower hub shaft flange of the helicopter.
As a result, Bond Air Services, who operate the aircraft on behalf of the Scottish Ambulance Service, decided to withdraw them from use.
The police helicopter was subjected to safety checks in July last year but was not withdrawn from service, police said.
An accident investigation team tasked by Eurocopter is assisting the AAIB and representatives from the French and German accident investigation authorities.
The European Aviation Safety Agency (EASA) and the UK Civil Aviation Authority are also involved.
A Eurocopter statement said: "Our thoughts are with the victims, their families, and the teams and individuals involved in the rescue operations."
Around 1,100 EC135 models are in service across the world, according to the company.
In the UK 57 are in operation, used mainly by the emergency services.