Chef Mark Reynolds saw the incident unfold while on a break from the Fox and Goose pub at Cooksmill Green where he works.
He said : "At first it looked like it was doing some kind of aerobatics but then I realised something was wrong.
"The engine seemed to have stalled and it just took a nosedive. I said to Mike - 'It's going down, it's going down' at which point we ran. I called the police and we ran towards the aircraft through the farmer's field. It was smoking at first and then set ablaze. There was nothing we could have done for those poor guys."
Both men are from Essex. Their names are expected to be released tomorrow.
Below is Malcolm Robertson's report: