Drunk after downing eight glasses of whisky with soda, an Australian transiting at Changi Airport climbed onto the Skytrain track at Terminal 3.

Kevin Patrick Flynn, 36, had earlier also clambered onto the zinc roof of a construction site behind Crowne Plaza hotel at about 9.30pm on July 17.

He was jailed for one week yesterday for criminal trespass. He was fined $1,000 for being drunk in public and causing an annoyance, and another $500 for breaking a fire hose reel glass panel that evening.

The delivery driver from Darwin pleaded guilty on Wednesday. Another charge of mischief by causing the zinc roof panelling to be dented was taken into consideration during his sentencing.

Investigations showed that he climbed onto the Skytrain tracks near the service road behind Crowne Plaza hotel.

He was drunk and ran around shouting on the tracks between Terminal 3 and Terminal 1, said Deputy Public Prosecutor Low Chun Yee.

He also tried to open the door of a parked Skytrain.

His presence and actions caused train services to be stopped for 11 minutes for his safety.

Services were disrupted again for half an hour the next day to retrieve his hand-carry bag, which he had left behind on the tracks.

He had also punched a fire hose glass panel , causing it to break.

His lawyer, Mr S. S. Dhillon, said in mitigation that Flynn was on a 15-hour transit en route to Cebu on July 16 when he asked a taxi driver to take him to the nearest pub.

However, he was taken to Orchard Towers, where an unknown man struck up a conversation with him at Top 5, a pub.

Mr Dhillon said Flynn took eight glasses of liquor and blacked out. The next thing he knew, he woke up in a taxi and realised he had been beaten up and his money was missing. He said his client could have been drugged, causing him to act in a bizarre manner.

He said Flynn, who has a 1 1/2-year-old son with his girlfriend in the Philippines, had no reason to come to Singapore on transit and go on a rampage.

District Judge Kamala Ponnampalam told Flynn that he had not only placed himself in danger but also caused disruption to the Skytrain service and inconvenience to the passengers by trespassing into a restricted area.

She also noted that he had caused damage to property totalling over $5,000 in all.

She agreed with the prosecution that the charges merited jail.

Flynn could have been jailed for up to three months and fined up to $1,500 for criminal trespass. The maximum penalty for mischief is one year's jail and a fine.