Eight Chinese nationals, who tried to steal from fellow airline passengers in separate incidents in July, were jailed between nine and 16 months' on Wednesday.
Senior District Judge See Kee Onn in July handed down a nine-month jail term for a similar offence, setting a benchmark for future cases. Then, he noted that such crimes were easy to commit but difficult to detect.
District Judge Christopher Goh noted as much on Wednesday while taking guilty pleas from the men. Referring to a recent rise in similar offences, the judge added that those convicted should expect an "extended" jail term.
Six of the men had worked in pairs and boarded the same flights intending to steal. The final two men had acted individually.
Senior District Judge See Kee Oon had said in July when sentencing two other Chinese nationals for such offences, that statistics showed an alarming rise in the number of similar reported cases. There were 43 last year, and 35 for the first 6½ months of this year.
Sentences passed in similar cases dealt with this year have generally ranged from six to 12 weeks. The maximum penalty is three years and a fine.