'Walk out for a ciggie' at 35,000 feet: the wild story behind Qantas's latest lifetime ban

Whether it's trying to open an emergency exit over the ocean or smashing a lemon meringue pie into a CEO's face, getting banned for life from an airline takes a special kind of chaos.

On May 15, a passenger allegedly attacked cabin crew members en route to the US, triggering an immediate lifetime ban from the Qantas Group.

But handing down a ban is the simple part. It gets a little trickier for airlines when it comes to enforcing the ban, but it can end in criminal charges.

Flight Attendant's Association of Australia (FAAA) federal secretary Teri O'Toole said that airlines tend to "err on the side of caution" and are not afraid to issue bans.

"Everyone forgets, a plane is literally a flying fuel tank. You do not want someone that you can't control on an aluminum tube full of fuel," she said.

"If cabin crew can't get a passenger to comply with direction, they're unsafe."

A flight from Melbourne to Dallas made an unexpected stop in Tahiti after a passenger allegedly attacked a cabin crew member.

The man was filmed by fellow passengers as he stumbled in the aisle, arguing with airline staff and attempting to "walk out for a ciggie".

While onlookers speculated the man was drunk, Ms O'Toole said that alcohol was not the trigger. Based on flight crew feedback, the passenger had only been served one or two drinks.

The passenger allegedly kicked, punched, spat and headbutted those around him, the union secretary said.

It took five people to subdue the man, with an able-bodied passenger forced to sit on him for hours until the flight reached Tahiti.

She said the plane landed in Papeete with the man still pinned on the floor.

"That means someone had to have sat on him all through landing ... the person that was restraining him was in danger as well," she said.

The passenger has been given a lifetime Qantas ban, with a spokesperson for the airline saying "the safety of our customers and our crew is our number one priority".

A lifetime travel ban from an airline is different from landing on a government no-fly list, which is reserved for terrorism or other national security threats, rather than drunk and disorderly behaviour.

Unlike a government watchlist, Australia's airlines don't share a centralised blacklist to flag difficult flyers to one another.

If a passenger is banned from one airline, they can cross the terminal and fly with a competitor.

According to Qantas conditions, the airline reserves the right to refuse carriage to any passenger who has failed to comply with their safety instructions, with bans extending across the Qantas Group network.

Because Qantas and Jetstar share corporate ownership and passenger databases, a ban from one automatically triggers a ban from the other.

But Australia's strict privacy laws prohibit airlines from sharing customer data, including blacklist databases, with competing companies.

"I don't know how [airlines] would do a centralised ban ... I think it would be difficult," Ms O'Toole said.

"You have to give people due process," she said.

If a passenger has been banned for life from an airline, alarms won't sound as they go through security.

Instead, their name, date of birth, passport number or Frequent Flyer details may be flagged by the booking system as the passenger attempts to book.

But if a banned passenger legally changes their name or alters its spelling, they may slip through the cracks and successfully book a ticket.

This is more likely to be successful when flying domestic, due to looser ID checks.

But it's a dangerous gamble. If the passenger is caught mid-flight or at the gate, they could be charged with trespassing or a range of other crimes.

The Australian Federal Police (AFP) may be called in, landing the banned passenger in legal trouble.

An AFP spokesperson said specific criminal charges would be based on "where the conduct occurred, how the person gained access, what directions were given, and whether any Commonwealth, state, or territory laws were breached".

The AFP has a zero-tolerance policy for air rage, saying the agency "works closely with the airline industry to intervene if anyone's behaviour interferes with the safety of workers or the public in or around an airport, or on flights".