Airports seem to exist outside of the realms of regular time and space. While you might be setting off on an early morning flight, someone else passing through on a layover could be eyeing up what to have for dinner.It’s part of the reason why you’ll find breakfast and dinner being served all day – and pints. It’s become so normalised that nobody blinks an eye at the sight of people clinking glasses of prosecco at 7am, but Ryanair boss Michael O’Leary has called to ban the practice.He claims that almost one flight a day on Europe’s busiest airline is being diverted due to unruly behaviour, which mostly stems from said passengers having had a few too many drinks before crossing the jet bridge.“It’s becoming a real challenge for all airlines,” O’Leary told The Times. “I fail to understand why anybody in airports bars is serving people at five or six o’clock in the morning. Who needs to be drinking beer at that time?”Given many passengers will be having their first meal of the day with their pre-pint flight, and some may not eat anything at all, you can see how issues arise.O’Leary has been an outspoken critic of the free-flow of booze at airports, and he repeated his calls for a two-drink limit, which would be enforced by having to show your boarding pass at the time of ordering.Ryanair has a zero tolerance policy for disruptive behaviour, and regularly shares updates about passengers who have been convicted due to their conduct on board.This week, the airline shared that two passengers who caused a flight from London Stansted to Ibiza to be diverted to Toulouse were given suspended sentences up to 10 months and a combined penalty of more than €10,000.However, not everyone is happy about O’Leary’s calls for a limit on drinks. Sir Tim Martin, owner of the British pub chain Wetherspoon, weighed in by saying a limit would be “extraordinarily difficult to implement, short of breathalysing passengers”.The chain told The Times that analysis of sales at its airport pubs over the past six months showed that a “significant proportion” of alcoholic drinks were ordered alongside a meal.It added that its pubs have strict rules in place to prevent passengers drinking too much before a flight, and that any limit could mean travellers instead drink before even getting to the airport.What are the rules about being drunk on flights?Rules around being drunk on flights are set by an individual country’s aviation authorities, but some airlines may also mention this in the conditions of carriage.For example, according to the UK’s Air Navigation Order 2016, “a person must not enter any aircraft when drunk, or be drunk in any aircraft” – but it does not strictly define what constitutes being drunk.In Lufthansa’s conditions of carriage, you may be refused boarding if “your conduct, your condition or frame of mind or physical state, for example, including the effects of alcohol or drug use, are such that you are a danger to yourself, to other passengers or to members of the crew”.In 2019, the European Union Aviation Safety Agency launched its #NotOnMyFlight campaign to stop bad behaviour, including intoxication and aggression on board.