Even since the golden age of aviation in the 1960s, airport slots have come at a premium. In 2016, for instance, a couple of take-off and landing slots at London Heathrow Airport were reportedly sold for close to $75m. 

And there is a school of thought that suggests the WSG, as supported by IATA, have done more than harm than good when it comes to solving capacity issues. Andrew Charlton, an aviation consultant – and former head of government affairs at IATA – is unsparing in his thoughts on the current guidelines: “They are totally out of date and out of time,” he says. “They stem from a construct of the 1970s – totally irrelevant to the way aviation is run and managed today.”

The most common gripe with the WSG is that they can be easily manipulated. As part of the current “use it or lose it” ruling, airlines can only keep hold of an existing slot at an airport from the previous year if they have used said slot 80% of the time. 

While the idea is that this allows new carriers allocation opportunities –  in the name of fairness and transparency – there is little to suggest that this is the case. According to one piece of analysis from 2017, only 0.4% of Heathrow’s slots were allocated to new entrants throughout the same study.

Some, such as Charlton, also suspect some airlines to be guilty of chicanery, such as flying smaller aircraft simply as a means of spreading their capacity across their slots – in, turn, allowing them to retain said slots. 

“The IATA call verges on the deceitful,” insists Charlton, an avowed advocate of slot reform. “The Worldwide Slot Guidelines are three words; three lies. The slot rules are an example of what Hamlet laments as the liberty the rich man takes of the poor.  

“Economists will tell you that windfall gain is evidence that the market is not working.  Slots are not, and do not need to be managed in a global way. There is no relationship between arrivals and departures.  Yes, of course the airlines have to make sure they match, but that is no reason to change the slot holdings of other airlines. They need total reform.”

“A transparent framework for slot usage is the best means to address this,” says Strickland. “There are complications however and the principles of fairness and equality must be respected, permitting airlines to plan capacity usage in a way that fosters long-term sustainable business whilst aiding meaningful competition.”

While it insists the WSG is no replacement for the provision of more airport capacity, IATA remains adamant that the current guidelines are for the greater good, insisting they are fair – even more so since independent slot coordinators were introduced in the 1990s. The body also points to capacity reviews as a sound means of adjudicating the capacity potential of an airport’s infrastructure. 

“In Europe, which is home to more than half of all the slot-constrained airports, low-cost carrier market penetration has risen to 40% over the last decade,” claimed de Juniac.

With plans to build a third runway at Heathrow, Charlton is drawn to speculate what that could mean for carriers vying to get lucky on what he describes as the hub’s “third slot machine”. He is no believer in slot auctions as a way of distributing what might, one day in the future, be one of aviation’s most desirable resources.

“The purists will note that the economically efficient way to distribute a scarce resource is to auction them, but such is their scarcity and their value to BA – and its partners –  that it is difficult to see how that will resolve much,” he says.

“It will make the slots more expensive, but it would not introduce any competition or benefit for anyone that is not a BA Frequent Flyer. There is also a fundamental question of who should get the proceeds of such an auction. It could be the UK itself, or Heathrow. Each would welcome the windfall gain that normally only falls on legacy airlines, but there are strong arguments against an auction in this case because it will fail to address a number of other real-world issues.”

Instead, allowing low-cost carriers – as opposed to the likes of BA –  in on the slot action at a new runway at Heathrow, could stir up welcome competition. 

“Other airlines, including low-cost carriers, are also keen to get into Heathrow,” says Charlton.  “That would make things more competitive. If the current slot rules, or auctions, are applied, there is no competition analysis or an assessment of things like dominance, and its impact on an airport of such national importance.”