A coroner's jury has ruled that a helicopter crash which killed Tory peer Lord Ballyedmond and three others was an accident.
Lord Ballyedmond, also known as Dr Edward Haughey, was killed when the AgustaWestland AW139 came down in a field in heavy fog shortly after take-off from the estate he owned in Gillingham, Norfolk, on March 13 2014.
Dr Haughey's foreman, Declan Small, 42, of Mayobridge, Co Down, Northern Ireland; pilot Captain Carl Dickerson, 36, of Thornton, Lancashire; and co-pilot Captain Lee Hoyle, 45, of Macclesfield, Cheshire, also died.
On Friday a jury inquest in Norwich ruled that their deaths were accidental.
Coroner Jacqueline Lake expressed her sympathies to family members, including Dr Haughey's wife Lady Ballyedmond, son Edward Haughey and the pilot's wives, who were in court throughout.
Excerpts of a cockpit recording were read out during the inquest.
In it, one of the pilots, who cannot be identified from the recording, is heard saying: "I don't mind telling you I'm not very happy about lifting out of here."
Air Accidents Investigation Branch (AAIB) expert Tim Atkinson said that had the helicopter been at a licensed aerodrome, it would not have been allowed to take off in such fog. Private helipads are not subject to such regulations.
Another AAIB investigator, Peter Wivell, said the pilot may have suffered from an optical illusion caused by the fog.
A lack of visual cues could have caused him to become disorientated and he may have felt like he was pitching up when he was in fact flying level meaning he over-corrected and steered the nose down.
No mechanical defects were found on the helicopter, he added.
Earlier the inquest was shown mobile phone footage of the helicopter taking off.
The person filming is heard remarking: "They're taking off blind."
The inquest has heard Mr Dickerson had warned the helicopter needed to take off "no later than 7pm" because of bad weather.
It did not in fact take off until 7.22pm as Dr Haughey oversaw the hanging of pictures as part of his renovation of Gillingham Hall.
Dr Haughey, 70, who lived at Ballyedmond Castle in Co Down, Northern Ireland, was considered to be one of Ireland's richest men, with estimated wealth in excess of £800 million.
Best known as chairman and founder of Norbrook Laboratories, the largest privately owned pharmaceutical company in the world, father-of-three Dr Haughey had a range of other business interests.
A life peer with a seat in the House of Lords, first on behalf of the Ulster Unionist Party before switching to the Conservative Party, he had also previously sat in the upper house of the Republic of Ireland's parliament, the Seanad.
James Healy-Pratt, solicitor for the Ballyedmond and Small families, said they were pleased the inquest had established the helicopter was fully airworthy and had advanced safety systems, that the pilots were fully qualified and trained, and that proper procedures were in place.
He added: "It is still a mystery why the pilots did not comply with the operations manual and adopt safe take-off procedures, or why they chose to deselect the autopilot, whilst attempting to take off at night in dense fog.
"The families continue to believe after this week of evidence that this was a preventable accident.
"We urge the Civil Aviation Authority to expedite the application of long overdue regulations, expected to come into force in August 2016.
"This is essential to prevent the loss of more innocent lives in similar circumstances."
The families of Mr Dickerson and Mr Hoyle declined to comment.
Ms Lake intends to write a report making recommendations about regulations governing private aircraft taking off from private airfields.