A pilot from South Gloucestershire had failed to properly plan his route or take account of poor weather conditions, an inquest heard.
Sharif Booz, his wife Margaret, son Ayman, and his schoolmate Charlie Froud died in the crash in 2008.
A hearing at Flax Bourton was told that Mr Booz, of Almondsbury, became disorientated in a storm over the Wicklow Mountains in Ireland.
Acting coroner Maria Voisin recorded a narrative verdict.
The court was told Mr Booz, a 43-year-old letting agent, was an experienced pilot who was taking his family from Staverton Airport near Gloucester to meet his wife's relatives at Kilkrush, County Kildare.
Ayman had brought his best friend Charlie, from Over, along. Both boys were 14 and pupils at Marlwood School in Alveston.
Irish Air Traffic Control lost contact with the Piper PA-28 plane for six hours on 25 October, 2008 and the next day rescuers found the wreckage on Corriebracks mountain.
The area, 20 miles from the party's destination, was affected by high winds, rain and poor visibility at the time of the crash.
Ms Voisin told the inquest she had "nothing to add" to the findings of an Irish investigation last year which found that Mr Booz planned his flight path into unsafe weather conditions and had not informed Kilrush Airport of his planned arrival.
He didn't have suitably marked charts or a flight log, and was flying too low in poor visibility, experts concluded.
The funeral of Mr Booz, who was of Egyptian origin, his Irish-born wife and the two teenagers was attended by more than 400 people.
A post-mortem examination in Ireland had found that all four died from multiple injuries.
Ms Voisin said the deaths were "an absolute tragedy".
"All that really remains for me is to express my deepest sympathies for your loss," she told members of both families at the inquest.