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US authorities searching for missing Australian soldier Paul McKay in dense forest in upstate New York are also monitoring airports in New Jersey and Los Angeles in the hope he arrives for his flight back to Australia.
McKay, 31, who was suffering post-traumatic stress disorder and was on leave from the Australian Army, sent an email to his father on December 30.
McKay wrote in the email he was leaving all of his possessions to his father.
Search teams led by New York Forest Rangers and volunteers have been focusing their search near Scarface Mountain in the Adirondack Mountains, where a person fitting McKay's description was seen on December 31 walking on train tracks.
Saranac Lake police chief Bruce Nason said McKay had bought a roundtrip ticket from Australia to the US and on Wednesday he was ticketed to fly out of Newark's Liberty International Airport in New Jersey to Los Angeles.
Then from Los Angeles he was scheduled to fly back to Australia.
"I would be very happy if he got on that plane," Chief Nason told AAP.
"That would mean he was OK and on his way home."
The Transport Security Administration (TSA), airlines and airports have been alerted to be on the lookout for Canberra-based McKay.
The Afghanistan veteran went missing when the northeast US was hit by the polar vortex, but Chief Nason said McKay's Army training gave searchers and his family hope he could survive the minus 30 degree Celsius temperatures and snow storms.
"Based upon his experiences, if anybody has a chance of going into this wooded area and coming out it is him," Chief Nason said.
"He has some experience.
"We are hoping he got slowed down by the weather.
"I remain optimistic.
"If I wasn't, we wouldn't be looking that hard and if it was my child I would want everybody to remain optimistic and we are.
"We are committed to continue the search for as long as it takes."