A 27-year-old passenger was arrested for smoking onboard IndiGo's Abu Dhabi-Mumbai flight, police said on Tuesday.
The flight's smoke alarm went off after the accused, identified as Tushar Chowdhary, lit a cigarette in the toilet of the aircraft while it was mid-air on Monday, senior police inspector Shashikant Mane said.
The flight staff rushed to the toilet and tried to open its door, but found it locked from inside, he said.
They kept knocking at the door, but when Mr Chowdhary did not come out, they opened it with the help of a key and found the passenger smoking a cigarette in the toilet, the police officer said.
When the flight landed in Mumbai, Mr Chowdhary was arrested by police, he said.
The accused was later produced before a court which remanded him in police custody, he added.
Smoking cigarettes or anything that produces smoke or flame is prohibited onboard most commercial aircraft.