New information has emerged that the missing FIFO worker ordered a taxi an hour-and-a-half after he was dropped off at Perth airport to Trigg Beach, in Perth’s Northern Suburbs.

William Carter, also known as Bill, was then last seen near the local surf club at about 2.40pm.

The 25-year-old’s mother, Jenny O’Byrne, had dropped Bill off at Perth Airport’s Terminal 3 at 12:40pm after having breakfast together.

Mr Carter was due to board a flight to his job at a job site near Karratha later that day, but never did.

Mr Carter took this selfie with his mum just hours before disappearing.

Police on Thursday revealed Mr Carter was at the airport for an hour-and-a-half before he ordered a taxi to Trigg Beach, in Perth’s northern suburbs.

9 News reports he was last seen near a surf club on West Coast Dr.

The FIFO worker’s partner Janae Williamson said that Mr Carter’s employer confirmed to her that he did not board the flight.

He was last seen at Perth Airport’s Terminal 3 on Saturday afternoon.

His loved ones are desperately searching for answers about his location.

“He’s not well, and he’s very vulnerable and at risk and we just need a lot of people to keep their eyes out,” his mother told PerthNow.

Bill Carter ordered a taxi half an hour after he was dropped off at Perth airport to Trigg Beach, in Perth’s Northern Suburbs.

“This is completely out of character for him, he has been displaying some quite bizarre behaviours, he does normally take anxiety medication but he’s been off that for about the last five months and that was a scheduled tailoring off”.

“But I think there’s been some other things that have gone on in his life, a situational crisis, and that’s so often the case in the mental health field.”

His partner is “begging” him to come home.

His mother says Bill is “ a very quiet affable chap” and has recently gone through “some challenges” and says because he is not very talkative some of those challenges have been missed.

Jenny O’Byrne told PerthNow Bill had recently returned from a family holiday to visit his father in Zambia. Picture: Supplied

“As a family we’re very supportive, I spoke to him a little bit on Saturday about what his concerns were, told him he has the full support of the family.

“We’re financially very solvent here and overseas, it’s just simply a case of when someone’s not well and they’re going through a situational crisis they don’t see the world as we would see it, they see it altered.”

A missing persons investigation is now under way, with WA Police looking into what happened to Mr Carter.

He is described as being approximately 174cm tall, of slim build, with brown hair and blue eyes. He was last seen carrying a small backpack and wearing a black t-shirt, shorts and white sneakers.

Anyone with information is urged to contact Police.

Don’t go it alone. Please reach out for help.

Lifeline: 13 11 14 or lifeline.org.au

Beyond Blue: 1300 22 4636 or beyondblue.org.au

Kids Helpline: 1800 55 1800 or kidshelpline.com.au

Headspace: 1800 650 890 or headspace.org.au

13YARN: Speak to Aboriginal and Torres Strait Islander crisis supporter on 13 92 76 or visit 13yarn.org.au