MIAMI — What makes someone get drunk and act up on an airliner?

In some cases, of course, it’s a fear of flying; most of us will at some point have come across the unfortunate traveler who grips his armrests with white-knuckled hands and looks as though he would rather be facing a great white shark a mile from the nearest beach than be in a pressurized metal tube kept aloft by a stream of superheated air and the mysteries of aerodynamics.

Their answer to ease their fear is booze, and that tactic can backfire at FL370 if the cabin crew start declining the passenger further alcohol.

That behavior, while regrettable, is perhaps understandable. Less easy to comprehend are people – usually young men – who get tanked up even before they get on board an aircraft, open their duty-free bottles on board, treat the flight attendants like bar staff, then get into arguments with traveling companions or complete strangers.

Bonus Flashback: Tri-Jet Twilight Inflight! Onboard one of the last MD-11 Flights 

That can lead to confrontations with passengers and crew. In worst case scenarios, the inebriated have to be physically restrained and handcuffed to their chairs.

Is There Any Restriction For This?

In 2016, IATA said it had recorded more than 10,800 unruly passenger incidents in 2015, compared to 9,300 in 2014. That equated to an incident every 1,205 flights.

“The anti-social behavior of a tiny minority of customers can have unpleasant consequences for the safety and comfort of all on board, said IATA director-general and CEO Alexandre de Juniac at the time. “The increase in reported incidents tells us that more effective deterrents are needed.”

IATA noted that alcohol or drug intoxication was a factor in 23% of those cases – mostly consumed even before the passengers got onboard.

This week Ryanair, Europe’s largest low-cost carrier, called for passengers to be served a maximum of two drinks at airports prior to boarding. It suggested such a rule could be enforced by means of passengers presenting their boarding cards every time they bought a drink in the airport, with the card being stamped accordingly.

Its proposal came in the wake of a BBC report that found a major rise in drunken incidents on board UK airliners, with 387 people arrested in the year to February 2017 compared to 255 in the preceding 12 months.

Going back further in time, the BBC obtained figures from the UK aviation regulator, the CAA, that showed an astonishing 600% rise in disruptive passenger incidents between 2012 and 2016, with most of those involving alcohol.

Ryanair also wants a ban on the sale of all alcohol in airport bars and restaurants before 10 am; another UK low-cost carrier, Jet2, already enforces an early-morning booze ban on board its flights.

“This is a particular problem during flight delays when airports apply no limit to the sale of alcohol in airside bars and restaurants. This is an issue which the airports must now address,” said Ryanair’s chief marketing officer Kenny Jacobs.

The UK Airport Operators Association introduced a voluntary code of practice in 2016 to tackle the problem, but clamping down on the sale of alcohol could hurt many of its concessionaires.

It argues that the code of practice can be adapted to changing circumstances quickly, rather than government imposing more laws to solve the problem. Existing laws are, in any case, perfectly adequate to deal with drunkenness at airports or on board – if they are enforced.

That enforcement can be a problem on international services. Offences that take place in international airspace, for example, have until now been outside the jurisdiction of the police at whichever airport the aircraft lands.

ICAO is attempting to close this loophole by the Montreal Protocol adopted in 2014. This would allow states other than the state to which an aircraft is registered to exercise jurisdiction over unruly passengers.

So far, however, few countries have ratified the protocol. Of course, gate staff have the option of stopping anyone obviously intoxicated getting on board a flight, but this option is seemingly rarely exercised.

Most of the UK’s problem revolves around flights to Mediterranean destinations popular with young people and well known for riotous behavior, such as Alicante and Ibiza in Spain and some of the Greek islands. Young adults go for a week of sun and booze and decide to start the holiday before they even set foot in the foreign country.

However, even unlikely routes can be subject to problems. This reporter was startled, some years ago on a London-Tokyo flight, to hear a public address announcement shortly after take-off, the nub of which was that cabin crew would be limiting the number of drinks served to customers.

A discreet chat with cabin crew elicited the information that the long flight, combined with the genetic inability of Japanese people to tolerate large quantities of alcohol, had led to several incidents on board that airline – especially in the business-class cabin.

Not Every Region Is Facing The Same Problem

Interestingly, the problem of onboard drunks seems more muted in the U.S.

Airlines for America (A4A), the country’s airline industry lobbying body said that onboard passenger disruptions were rare.

When they occurred, however, “A4A has supported vigorous prosecution of passengers charged with disruptive behavior aboard aircraft,” said a spokeswoman.

As part of the FAA’s Reauthorization Bill passed in 2000, the FAA can propose fines of up to $25,000 per violation for unruly passenger cases. Previously, the maximum civil penalty per violation was $1,000. One incident can result in multiple violations.

Those hefty penalties perhaps explain why the frequency of incidents involving problem passengers is considerably lower in the U.S. than the UK.

Additionally, the thought that there may, just conceivably, be an armed air marshal on board may be enough to stop a drunk U.S. traveler from kicking off.

Whatever the reason, FAA statistics show a high-water mark of 310 ‘unruly passenger’ incidents in 2004; ever since then, the trend has been steadily downwards. In 2015, it was 105; in 2016, 97; and halfway through this year, it was a remarkably low 22.

(The FAA statistics do not separate out ‘unruly passenger’ incidents into categories such as anger over a severely-delayed flight, ‘bumping’ or drunkenness.)

Underlying the problem of onboard drunkenness, of course, are changing social customs. Readers will be familiar with photographs of well-dressed passengers on 1950s and ‘60s airliners.

Today, few people dress up to take a flight and standards of behavior in wider society have dropped. And the affordability of flights today means that many people can fly who would simply have been unable to do so in previous decades.

PHOTO: National Air and Space Museum, Smithsonian Institution.

Op-Ed: Should Dress Code for Flying Passengers Be A Thing

And, in the past, if trouble was brewing in the cabin, it was not unknown for flight deck crew to appear. A sharp word from an authority figure bedecked in gold braid and a peaked cap was often enough to defuse a simmering situation.

Now, however, not only has respect for such authority largely vanished, for reasons of security pilots are no longer allowed to leave the flight deck to tackle such situations.

Perhaps, five years down the road, we’ll be queuing at airport bars, offering not only money but those boarding cards to get our hands on a beer.