Aviation expert Paul Beaver has been talking to ITV News. He said "It's a very perplexing case. You have a very sophisticated helicopter with very well trained crew at the top of their game, flying on a night when the weather isn't particularly bad,
"It's blustery but not out of the limits of the helicopter, and doing something tat it was built to do which is fly at very low level at night."
He went on to say that since the Glasgow helicopter crash last month and last night's incident there have been around 90,000 helicopter flights without incident.
RAF Marham's station commander has spoken about the base's role in the investigation into last week's helicopter crash in north Norfolk.
Churches in our region have been lighting candles in memory of the American air crew killed when their helicopter crashed in Norfolk.
Last year the US Airforce published a story on the importance of helicopter training missions.