The family of Lord Ballyedmond have said "serious questions" remain over the death of the life peer in a helicopter crash.
A coroner's jury yesterday ruled the incident that killed Northern Ireland's richest man and three others an accident.
Lord Ballyedmond, also known as Dr Edward Haughey, died when the AgustaWestland AW139 came down in a field in heavy fog 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; pilot Captain Carl Dickerson (36), of Thornton, Lancashire; and co-pilot Captain Lee Hoyle (45), of Macclesfield, Cheshire, also died.
At the end of the hearing coroner Jacqueline Lake expressed sympathy for family members, including Dr Haughey's wife Lady Ballyedmond, and the pilots' wives, who were in court.
But a statement released afterwards on behalf of the Ballyedmond and Small families said serious questions needed to be answered. It read: "It is a mystery why the pilots did not comply with the operations manual and adopt safe take-off procedures, or why they deselected the autopilot whilst attempting to take off at night in dense fog.
"The families continue to believe 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."
Excerpts of a cockpit recording were read out during the inquest yesterday. In them one of the pilots, who cannot be identified, 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.
Another AAIB investigator, Peter Wivell, said the pilot may have suffered from an optical illusion caused by the fog, claiming a lack of visual cues could have caused him to become disorientated at the controls. No mechanical defects were found on the helicopter, he added.
Earlier the inquest was shown footage of the helicopter taking off. A person filming is heard saying: "They're taking off blind."
The inquest had heard Mr Dickerson 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 a renovation of Gillingham Hall.
The 70-year-old, who lived at Ballyedmond Castle in Co Down, had an estimated wealth in excess of £800m.
Known as founder of Norbrook Laboratories, the largest privately owned pharmaceutical firm in the world, the father-of-three had a range of other business interests.
A life peer in the House of Lords - first on behalf of the UUP before switching to the Conservative Party - he had also previously sat in the upper house of the Republic of Ireland's parliament, the Seanad.