But downing a bottle of vodka in the airport toilets derailed those plans.
The Qantas flight had been taxiing to the runway when the alleged incident happened.
The female victim was seated in front of the defendant.
"You pushed your arm through the gap in the seat, grabbed her breast and squeezed it," Judge Moses said.
When the man sitting next to Gunaskera objected to his behaviour he was met with a barrage of abuse, before the defendant was removed from the flight.
Defence counsel John Munro said his client downed a whole bottle of vodka in the toilets before the incident and could not remember anything.
"He's feeling really, really embarrassed by what he did," he said.
Since the incident, Gunasekera had accepted he was an alcoholic and attended a residential rehabilitation programme for a week.
Mr Munro described the fiasco as a "blessing in disguise", which had allowed the 33-year-old to address his destructive behaviour.
Gunasekera had since been taking medicine that made him violently ill if he consumed any alcohol.
Judge Moses condemned the defendant's behaviour and said the fact he was blind drunk at the time was not an excuse or mitigation.
"Members of the public travelling on planes have a legitimate expectation that they can do so without being groped or abused like these victims were by you," he said.
About half of the fine money would be paid to the victims as emotional harm reparation, the judge ordered.
