If you have ever heard airline staff talking about a flying slot for airplanes at busy airports and wondered what they are and why we need them, then read on! This article exposes the dark side of flying slots and how airports, airlines, and flight crews manage them.
Pilots pride themselves on developing and refining their craft to achieve the mission. Their mission, which they choose to accept, is to get their airplane from A to B safely and within the mission parameters. In an airline environment, schedule is an everyday focus and one thing that challenges that is flying slots for their airplanes at busy airports. Most airlines will have a mantra they teach their flight crew which is the priority they expect flight crew to adhere to. In order of priority, it is generally something like Safety, Comfort, Schedule, and Economy.
What it means for pilots is when it comes down to it, safety is first at all costs. If then, safety can be maintained, then comfort and schedule are next. Pilots strive to make sure their own processes are efficient to avoid delays, by using checklists for example, however, airport flying slots are something that can take some of the fun away and need to be managed. Flying slots if used well, can maximise the flow of air traffic into a busy airport and there is an art form in achieving them.
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What is a flying slot time?
A flying slot time is a regulated window of time that the air management service at an airport assigns to a flight that is an allocation of a permitted time to take off or land (takeoff slot or landing slots). They are referred to by different names depending on the local region but have the same purpose of managing the flow of air traffic. Other names are slot times, calculated off blocks time (COBT), calculated take-off time (CTOT) or airport slots.
Many major airports have flying slot times and generally the busier the airport, the more widely used the flying slot times. If you were a fly on the wall of any flight deck, notification of a flying slot time brings with it the combination of eye rolls and sighs from most pilots as pride is taken from being disciplined and methodical to not be the source of a delay so when a flying slot is issued, all their best efforts become invalid.
How do you get a flying slot time?
Each country has government regulations in the management of flying slot times which determines how the flying slots will be fairly applied. Underpinning the overarching regulations is individual airport requirements that consider historical hours of congestion and foreseen day-to-day effects such as weather. Each individual airline or operator then reviews the desired schedule and applies for the flying slot from the airport authority and sometimes negotiates or influences how many they get.
This is where it can get interesting as the airline players vie for as many as they can get seeking commercial advantage. Flying slots are like gold and the challenge for an airline is to manage commercial issues such as unplanned breakdowns or weather delays down port. Airline operations coordinate the assigned flying slots and advise flight planning and the pilot directly so that they can be enacted.
What needs to occur during a flying slot time?
When a flight crew is preparing an airplane for departure, awareness of their assigned flying slot time is imperative as they need to make decisions on fuel, communicate with operations, airport operators and ground staff, advise cabin crew and passengers as well as review their flight duty period. A flying slot time can be a window that you must push back in, arrive at an arrival waypoint or take-off.
Flight crew must manage their workload to assist in achieving the window which often have a 15-minute buffer to allow for minor delays.
What happens if a plane misses its take-off flying slot?
Flight crew needs to demonstrate many professional competencies when managing a flying slot time such as workload management, leadership, and teamwork, and problem-solving and decision-making. If an airplane misses a take-off flying slot this can pose additional pressure and increased workload for the flight crew.
There is a commercial cost to missing a take-off flying slot as another slot will need to be applied for which can mean a delay of several hours. If this occurs, the take-off is delayed until another slot is found, and managing the disruption to passengers can be a substantial commercial cost to the airline business. Although most countries do not have a direct fine the cost can still be high for missing a flying slot.
There have been some models of flying slots where flights can still depart but the fuel penalty is high through many hours of holding airborne which makes it untenable to an airline. An airline’s operations department is usually in the loop to manage this situation as they may be able to swap a slot with another flight or combine two flights together as part of their overall schedule recovery for the day. This can be tricky for the flight crew and much care needs to be taken not to rush and increase the chance of an error in making the flying slot.
Can airplanes ever take off outside of their slot time?
An airplane may not be issued a take-off clearance if they are in breach of the flying slot so fooling the system is a bad option. The flight crew will coordinate closely with their operations department if they feel that their flight may not achieve the flying slot as they will need to consider the commercial cost of the disruption to the day of ops. Generally, the earlier a flight crew anticipates missing a slot and advises operations, the better they are to manage the disruption.
As you can imagine the ideal situation is to make the slot to avoid the commercial cost however flight crew need to be extremely cautious in managing the safety risk equation. As a passenger, you can understand why the ground staff have you lined up early and rush you onto the airplane if the flight is close to missing the window. The best thing passengers can do to help is to be close to the gate lounge and not go ‘missing’ in the airport bar!
How are flying slot times used to manage the flow of aircraft at busy airports?
If you imagine a crispy fry being dropped on the beach and observe the arrival of the flock of seagulls, then you are pretty close to what it would be like at a busy airport if flying slots were not used! If the number of desired scheduled flights were to go when they felt like it, the air traffic flow would be dangerous and difficult to manage. The available slots are determined by the capacity of the airport air traffic management system based on air traffic controller numbers and runway configuration.
By assigning a slot time to flights it allows airport coordination to separate flights in an organised way which consequently reduces airborne traffic delays.
Whose responsibility is it to manage flying slot times?
The responsibility of managing flying slot times falls on the air traffic management system in coordination with each individual airport. While the rules are set at the government level for a state or territory, the practical management of air traffic management slots is tailored to local conditions. Within an airline, the operations team coordinates how the airline prioritises their assigned slots and advises flight crew down the line.
Do flying slot times differ between airports?
Yes, flying slot times differ between airports due to different capacities of the local air traffic management capability, the available runway configuration, and the general congestion caused by demand.
The FAA (Federal Aviation Administration) actually uses runway slots to limit the scheduled air traffic at certain USA airports that have capacity constraints. Those airports are John F Kennedy International airport, Ronald Reagan Washington National airport, and LaGuardia Airport.
Do flying slot times differ between types of aircraft?
Flying slot times will vary not necessarily on aircraft type, but aircraft flight category. For example, each airport will have an agreed list of priorities such as scheduled regular public transport which would get priority over an aircraft charter flight and a training flight is even further down the list if at all approved at an airport.
Conclusion
If you have ever wondered how the busiest airport in the world can cope, then you should now understand that airport flying slots are a necessary evil. By the way, the busiest airport is Hartsfield–Jackson Atlanta International Airport processing 75,704,760 passengers in 2021. There is an unspoken pilot joke that airlines would run smoothly without passengers however they also know that passengers are the reason they get paid to do the job they love. Flying slots at busy airports are necessary. Period. They are not there to simply bug pilots or passengers, they are the reason that so many airplanes can arrive at the same place more often, safely.
Everyone gets to contribute to achieving a flying slot; air traffic control, mother nature and her weather, flight crew, ground crew, and believe it or not, even you the passenger. So, when you hear about flying slot, do not be mad, be part of the solution for a coordinated airport!
