I check in already & pass Immigration at SVB Airport, I would like to know if it's possible to change his mind & go back officially to Thailand?

Doubt it.

Best ask.

yeah right you did ...

Yes you can but they cancel your exit stamp

I smell someone who wants to fake his departure...

Danielsiam, I presume you mean BKK airport.

Yes, it is possible. You would not be the first to get scared of flying at the last moment and turn around. Just make sure you will not overstay by the time you will eventually depart.

He want his mia to think he's left the country 555

That reminds me, I must watch Bangkok Airport on iPlayer.

Danielsiam, I presume you mean BKK airport.

Yes, it is possible. You would not be the first to get scared of flying at the last moment and turn around. Just make sure you will not overstay by the time you will eventually depart.

But do note that they will simply cancel your departure stamp, you don't get a fresh entry.

An 'airside visa run' doesn't work.

A nice bit of lateral thinking there Crossy.

Yes you can but they cancel your exit stamp

I did it in 2010 told them mrs was ill but it was another reason. Was not actually that easy but they did not cancel my visa and I had no re entry permit, they just cancelled departure stamp.

That happened to me several years ago when Royal Nepal Airlines cabin crew tried to downgrade me after boarding. It was a very weird (and unpleasant) experience after which I refused to take any seat so was deplaned.

Thai immigration didn't care and in any case I had a re-entry permit but the departure stamp had a huge "CANCELLED" stamp put across it in bright red ink. Later an immigration officer in HK questioned me about why I had that stamp.

So unless unavoidable, I wouldn't recommend it.