More detail emerges:
One of the men had hired the Robinson R22 aircraft to take his friend on a flight.
The pilot, a 63-year-old man from south west Northumberland, and the passenger, a 75-year-old man from Gateshead, were taken to Newcastle General Hospital for treatment.
The aircraft is owned by Northumbria Helicopters, a flight training organisation based at the airport, and is normally used for training purposes.
Manager Neil Clark said the company had not experienced any such incidents in the five years it had been running flights.
A Northumbria Police spokesman said the Aircraft Accident Investigation Branch had been notified and would be carrying out an investigation.