A crew from the East Anglian Air Ambulance (EAAA) was called to help an elderly patient who had suffered a medical emergency in Wymondham on Thursday morning.
The helicopter landed on a small patch of grass between Fairland Street and Avenue Road after being called out at 9.13am.
An eyewitness said it was still there more than an hour later.
An EAAA spokesperson confirmed the crew had been called out to assist the East of England Ambulance Service.
Pilots Steve Norris and Henrietta Davies landed the helicopter so doctor Nicky Ueckerman and critical care paramedic Andy Downes could assess and treat the patient.
The patient was later taken to the Norfolk and Norwich University Hospital by land ambulance, at which point the EAAA team returned to base.
Also on Thursday, the air ambulance helped police and paramedics at the scene of a suspected industrial accident on a farm in Hainford, near Norwich.
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