The woman was standing on the ground, waiting to receive a private plane which friends of hers were flying. For reasons unknown, the woman was hit by the plane's propeller after landing.
The woman was initially taken to Södra Älvsborg's hospital, but from there moved to Sahlgrenska University Hospital in Gothenburg. According to a statement made on Saturday by Södra Älvsborg's hospital her condition was life-threatening.
Sahlgrenska was unwilling to comment on her condition on Sunday.
The plane was standing still and running idle when the accident occurred.
"When you turn off the motor, you follow a check list, and at that time the pilot might not have full attention to what's happening outside the plane," Börje Gustavsson, vice chairman of Borås's flying association, who run the air field in Viared, said to news agency TT.
"I saw out of the corner of my eye that someone came in diagonally from left towards the plane, and walked right into the propeller."
According to Börje Gustavsson, the entire air field has signs showing pedestrians where to go.
"Somehow something's gone wrong. Unfortunately this isn't the first time something like this happens in flight situations."
One of the flying association's members is a doctor, who performed first aid on the injured woman, who is in her seventies.
The accident is now being investigated by police, but may end up on the desk of the Swedish Accident Investigation Board (Haverikommissionen).