Lack of contact between police and air traffic control delayed a search for a crashed helicopter for more than four hours, a report has revealed.
The wreckage was found in the Blackdown Hills near Corfe
The crash on the Blackdown Hills, Somerset, in 2005 killed the pilot, two other men and a teenager.
The Air Accidents Investigation Branch (AAIB) said police got a 999 call reporting a "bang" early last year.
The AAIB said however, while the report was received at 1247 GMT on 22 January, a search did not start until 1717 GMT.
Pilot Roy Stevens, 54, Peter Bloxsome, 59, Allan Tartaglia, 44, his son James, 15, were all killed in the crash.
Mr Stevens was from Gotherington in Gloucestershire, Mr Bloxsome was from Cheltenham, Mr Tartaglia was from Brockworth and his son James was from Evesham in Worcestershire.
The report said that minutes before the emergency call the helicopter had been seen hovering near a camp site for four to five minutes and sounded "fine".
No flight plan
The helicopter was heading back to Staverton airfield in Gloucestershire, where it was normally based, when it got into trouble.
The pilot cut short its journey and stopped at a playing field in Topsham near Exeter.
Exeter Air Traffic Control became worried and rang Staverton when it did not hear from the pilot, who in turn tried to call the mobile phones of the pilot and passengers.
Allan Tartaglia and his son James died in the crash
A search and rescue operation, though, was not launched immediately because no flight plan had been logged and the helicopter was not considered "overdue".
The search, said the report, was hampered by snow during the evening and the wreckage was eventually found by a dog walker the next morning.
The report adds that although the weather was a key factor in the crash, Mr Stevens had been given a "limited amount of instrument only training".
"With the pilot's experience and the relatively low amount of instrument only flying training he had received, he would, at best, have found the conditions extremely challenging," said the report.