A large scale search and rescue effort has gone into its third day near Blackall after a infrared flyover overnight failed to find any sign of a missing 78-year-old woman.
Muriel "Ann" MacDonald was last seen by family at the 3200 hectare property Moorfield, on Ravensbourne Road, at 2pm on Wednesday.
There are currently 105 people involved in the search.
It's believed she left on foot, but it's unknown what direction she went in.
Police and family hold concerns for her wellbeing as she suffers from medical conditions, including poor vision.
Longreach Patrol Group's Inspector Julia Cook said there had been a wonderful response from the local community.
"We've got people out here searching on bikes, horses and on foot but unfortunately we're not having much luck," she said.
"We started with a 3km search radius and we're expanding from there."
The search is being conducted by State Emergency Service volunteers, government agencies, police from Charleville, Longreach, Blackall and Tambo as well as local residents.
Two helicopters have also been involved in the search, while a plane was flown in from Cairns last night to use infared technology to try to detect heat signatures that could lead rescuers to Mrs Macdonald's whereabouts.
Inspector Cook said hot day time temperatures were concerning and they hoped they could find Mrs MacDonald as soon as possible.
"There has been rain the last two nights she's been missing so that could be seen as a positive thing as there is water out there," she said.
"We are concerned she was disoriented so it's hard to know what direction she may have gone in."
Mrs MacDonald is described as Caucasian, around 160cm in height, of a solid build, with grey hair and dull blue eyes.
Anyone who believes they have seen her or with information on her whereabouts is asked to contact police urgently.