A logging worker has suffered head injuries after falling 200m down a bank between Blenheim and Picton.
The skidder driver was flown to Wellington Hospital in a serious condition after the accident this morning, St John said.
The Nelson Summit rescue helicopter couldn't fly in because of fog and asked their colleagues in Wellington to send in a chopper to the forest near Koromiko airfield.
A paramedic was winched to the man before he was taken to Wellington.
St John was alerted at 8.57am to an emergency call that the driver of the heavy machinery had tumbled two rugby fields down a bank.
A spokesman said he had possible head and chest injuries.
Picton Senior Constable Paul McKenzie said the skidder slid off the top of an access road and rolled into a cutover area in a narrow gully.