He could hear the planes and helicopters fly overhead, but he couldn't see them.
Lost in the harsh Australian outback, his mouth so dry his tongue felt like sandpaper, Sam Derry-Woodhead knew he had to get a message to those in the sky.
Taking a pair of old rugby shorts from his backpack, the young British teenager laid out the letters SOS.
The 18-year-old keen sportsman had weighted his backpack with clothes when he set out on an army-style 'yomp' from a remote Queensland homestead on Upshot Station.
He had found work at the cattle station as part of his gap year and set out for a run at 4.30pm last Tuesday, deciding to take a "quick-route" through thick scrub.
By nightfall, however, he was hopelessly lost.
He was reported missing on Wednesday morning.
The young teenager would find himself stranded in the unforgiving outback, starving, dehydrated and fearing dingo attacks, for three long days.
In a paid interview with the UK's Daily Mail, Mr Derry-Woodhead said he used all the clothes he had to make an SOS sign.
"I used jumpers, a couple of pairs of shorts and spread them out to make the SOS signal as big as possible. It was about 15 feet across," he said.
By then, he had spent two days in the searing heat, and was becoming increasingly hopeless.
"My mind was playing tricks on me and really tormenting me," he said.
"I started creating these personalities and talking to them, even though I knew they weren't real."
Among those characters was a military-style guard, who sprang to life whenever the teenager heard an animal noise, triggered, Mr Derry-Woodhead believes, by his fear of dingoes.
Coincidentally, Mr Derry-Woodhead's maternal grandfather was World War II hero Lieutenant-Colonel Sam Derry who helped rescue prisoners of war from Italy.
Unable to find water, he sipped the saline solution from packets of contact lenses, bought for him by his father, that he had stashed away in a compartment of his backpack.
The supply from the 150 sachets amounted to 200 millimetres - less than a soft drink can.
He had tried drinking his own urine, but found it unbearable.
Come Friday afternoon - three days after he was reported missing - an Emergency Management Queensland helicopter made another sweep of the area about 2.30pm.
Volunteers from as far as 320 kilometres away had responded to the call for help in the search. Cattle station owners manned their own aircraft, while State Emergency Service volunteers searched on foot.
Mr Derry-Woodhead watched in despair as the chopper looked to be disappearing in the distance.
"I thought, 'This is really it'," he said.
"I couldn't face trying to survive out there for another day. I either wanted to die or to be rescued. I just wanted it to end."
However, the helicopter suddenly turned around after one crew member spotted an object fly into the air.
That object was Mr Derry-Woodhead's pair of white rugby shorts.
"I asked the pilot afterwards and he said, 'the only reason we turned around was because we saw something fly up from the ground'," he said.
"It was a pair of my white rugby shorts that I used in the SOS sign.
"The crew had flown over and hadn't noticed the sign, but they were so low their rotors blew my shorts up into the air and that was what they saw. That was the reason why they turned around.
"They told me afterwards they only had 15 minutes of fuel left in the helicopter. If they hadn't spotted me when they did, they'd have gone away again."
So weak, Mr Derry-Woodhead could barely crawl by the time a bearded rescuer winched him to safety.
Throughout his three-day ordeal, Mr Derry-Woodhead was never more than 10 kilometres from the Vergemont homestead, had been simply zig-zagging his way through thick scrub.
Detective Senior Sergeant Dave Perry, who coordinated the search, said he believed the young teenager would not have survived another day.
"A lot of people were of the opinion that if he was found, then he wasn't going to be found alive," Sergeant Perry told ABC Radio.
"I probably had a little bit more information than what they did. I thought that he had one more day at least. We were still under pressure."
Sergeant Perry recalled being in at the makeshift command post he has established at the homestead when he heard over the radio, "We think we've found him."
"It was just all over from there," he said.
"If we would have been anything up to 12 hours later, he could have been deceased."
Mr Derry-Woodhead was taken to Longreach Hospital, where he has made a speedy recovery despite suffering kidney damage and losing about 15 kilograms. He was well enough on Sunday night to enjoy a pub meal with is family.
However, the ordeal has not dissuaded him from continuing on his gap year adventure, which includes hiking in the Himalayas.
"What has happened isn't going to put me off doing extreme sports, but it might make me think more about the things that can go wrong, and I will probably bring more water with me in future," he said.
It is understood Mr Derry-Woodhead will donate the proceeds of his undisclosed deal with the Daily Mail to the various organisations involved in the search for him.
- Brisbane Times