Air traffic at busy airports is controlled through the use of slots. A pair of slots gives an airline
the right to land and depart an aircraft (at specified times) and use airport facilities.
Guidelines exist to use and allocate available slots- something we’ll examine in today’s video.
Before we begin, we’ll have to apologize for having to say the word slot over and
over again. Unfortunately, there are few good synonyms for this word in an aviation context!
Airport arrivals and departures are controlled by a slot system that has been in place for
many years. Guidelines and definitions on slots are laid out by the International Air
Transport Association (IATA), with three airport categories, depending on capacity and demand:
Level 1 (a non-coordinated airport). Level 2 (a slot facilitated airport).
At level 1 and 2 airports, arrivals and departures are managed by the airport and
through cooperation between airlines. And Level 3 (a coordinated airport).
Slots are used at Level 3 airports. According to IATA, as of Summer 2019,
there were 205 slot coordinated airports globally, covering 43% of global air traffic.
The number of slot pairs is agreed upon and allocated to airlines at these airports.
IATA has a process in place to manage and re-allocate slots to airlines. This is known
as Worldwide Airport Slot Guidelines (W.A.S.G.)- a global standard, which IATA says ensures,
Certainty of access, Flexibility to mix and match slots,
Sustainability of costs, And transparency of allocation.
Key to slot allocations is a bi-annual review and re-allocation. IATA defines a
winter and a summer season each year, which is usually late March and late October.
Airlines can have different slot allocations for each season, with historical precedence as
the critical criteria in allocation. Airlines and airports must submit plans and requests in advance
and a slot conference is held before the start of each season
to finalize allocation for all airlines. Strict usage rules are in place at normal times.
If slots go unused for at least 80% of each season in normal circumstances, they will
be returned and re-allocated- although waivers have been in place for this during the pandemic.
There are rules in place to allocate a proportion of available slots to new entrants,
and there is a focus on ensuring this. The problems lie at the busiest airports,
where slots are simply not coming available. Referring to this, IATA explains its view,
"It may not be perfect, but challenges to the WASG are disproportionately focused
on London Heathrow and a very small number of other airports (Amsterdam,
Hong Kong) that are essentially in a separate category that could be called super congested."
Slot re-allocation works well only when there are slots available to be allocated.
IATA does not sell or facilitate bidding for slots, but trade between airlines is permitted.
Slots are a valuable airline asset at the busiest airports and are often traded.
As an extreme example, a pair of Heathrow slots was bought up by
Oman Air from Air France-KLM in 2016 for $75 million. Also, at London Heathrow,
Air New Zealand sold its slot pair in 2020 for about $27 million USD when it left the market.
Of course, not all slots are this expensive. Value depends on the airport, seasonality,
slot times, permitted turnaround time, and how frequently the airline needs to use the slot.
Other slot allocation methods have been proposed - such as auction-based systems
or congestion-based pricing, where airlines pay more to operate flights at peak hours.
These options also have their problems, and so it’s unlikely the current system will change soon.
What do you think about the slot allocation process?
How would you improve it? Let us know in the comments.