Eight Chinese nationals who tried to steal while travelling on Singapore airlines SilkAir and Tigerair in July and August had the book thrown at them, when they were sent to jail for between nine and 16 months.
"These despicable acts must be nipped in the bud before they get out of hand," said District Judge Christopher Goh.
He warned that anyone caught stealing luggage while in an airplane can expect an "extended" jail term.
There has been an alarming rise in the number of such cases - with 43 last year, and 35 in the first 6 months of this year.
In similar cases dealt with this year, sentences generally ranged from six to 12 weeks.
In July, Senior District Judge See Kee Oon set a benchmark punishment of nine months when he sentenced two other Chinese nationals, noting that such crimes were easy to commit but hard to detect.
Goh gave an indication of several aggravating circumstances which would increase the sentence.
The factors he considered included whether there had been "syndicated or group activity", the value of the items, and if the crooks had removed any loot or disposed of them.
Ren Jun, 33, and Li Xingwang, 34, received Wednesday's stiffest sentence of 16 months in jail, because the duo stole twice within a week. They took S$808.68 ($783) in cash on two SilkAir flights between Singapore and Kota Kinabalu.
Wang Xian Yin, 46, and Ding Chao, 35, were handed 14-month terms for stealing two bags while on a Tigerair flight from Jakarta, and a bag while on an earlier SilkAir flight from Singapore to Shenzhen.
During the Shenzhen trip, Ding took, rifled through and returned a bag to its overhead compartment as practice.
For stealing A$2,300 ($2634) during a SilkAir flight from Phnom Penh, Ding Mingquan, 50, and Huang Yonglong, 42, got 13 months each.
The final two men acted on their own. Ren Jia Qing, 41, who got a year in jail, tried stealing HK$13,000 ($2057) in cash on a Tigerair flight from Hong Kong.
Zuo Wubao, 39, who got nine months, had taken a backpack containing valuables worth S$3,040 ($2945) during a Tigerair flight from Phnom Penh.
All eight men, who faced a maximum penalty of three years and a fine, pleaded guilty.