IES86936B2 - A system and method for allocating a landing time slot to an aircraft at an airport - Google Patents

Abstract

The present teachings relates to a computer implemented method for allocating a landing time slot to an aircraft at an airport comprising allocating a predetermined landing time slot to the aircraft, receiving an notification indicating the time that the aircraft departed from its origin, determining that the predetermined landing time slot is not compatible with the arrival time of the aircraft based on the departure time of the aircraft, initiating a slot assignment algorithm to search for an alternative landing time slot based on an arrival time of the aircraft at the airport, the alternative landing lot being an available landing time slot in a sequence of available landing slots as close to the arrival time as possible, and assigning the alternative landing time slot to the aircraft. <Figure 1>

Description

1) An airline prepares a specific flight plan in line with regulatory and industry protocols. It also considers known operational variables on the day of landing and allows for contingencies (e.g. alternate destination fuel). There can be several drafts for a flight plan in advance of departure, with the final version being signed-off by the captain. 2) The flight takes off in line with normal airline, airport and Air Traffic Management (ATM) procedures. Usually a departure slot will be allocated to flights, particularly at IATA Level 3 and Level 2 congested airports. This has no bearing on the arrival time and simply allows the aircraft to depart and move into the airspace identified in the flight plan. 3) Once an aircraft is airborne ("wheels-up) the on-board Flight Management System (FMS) sends an airborne message (the ‘alert ping’) from the aircraft to the airlines Operations Control Centre (OCC) through the Aircraft Communications Addressing and Reporting System (ACARS) communications system. Similar alerts are sent at regular intervals throughout a flight’s progression, when the aircraft passes through predetermined wayfinding points along its flight plan route. This allows the airline to track the aircraft at all stages throughout the flight. 3) Approach control or terminal control (at an airport) co-ordinates arrival slots in line with airfield operations on the day through its Arrivals Manager (A-MAN) system. That is, landing slots are co-ordinated and allocated by the Air Traffic Management provider (ATM) in line with airfield capacity and operational constraints on the day. 4) As the aircraft passes through various jurisdictions it may be instructed to move its position, height or speed and this will have an impact on its eventual arrival time.

) Any change is input to the Flight Management System (FMS) and this regulates the flight in terms of time. Positional alert messages are relayed to the airline’s Operations Control Centre (OCC) via the ACARS system which allows the airline to monitor the progress of the flight. 6) In the ideal scenario flights will land when they reach the airport and when an aircraft reaches approach it requests a landing slot. Approach Control regulates aircraft landing in line with airfield capacity on the day. This is subject to many variables: weather, airfield congestion, operational delays or medical emergencies; all which impact on air traffic management flow. 7) As is often the case in busier airports, Approach Control may advise a flight to hold for a period until a landing slot becomes available. 8) Once an aircraft is advised to hold it will be placed in a stack or extended vector until it is given approval to land. This can be for up to 20 minutes, or longer if operational constraints on the day are extreme. 9) Eventually, aircraft will be given clearance to land and called out of the stack when a landing slot is available.

It is clear from the above outline that the biggest issue with the conventional process for landing aircraft at an airport is that aircraft can be left in a holding pattern above the airport. This uses up valuable fuel leading to increased pollution as well as inconveniencing passengers.

Accordingly, there is a need for a system and method that more efficiently allocates landing time slots to aircraft such that they are not placed in a holding pattern or minimises the aircraft time in the holding pattern.

Summary According to the present invention there is provided 1 a computer implemented method for allocating a landing time slot to an aircraft at an airport comprising allocating a predetermined landing time slot to the aircraft, receiving an notification indicating the time that the aircraft departed from its origin, determining that the predetermined landing time slot is not compatible with an arrival time of the aircraft based on the time that the aircraft departed, initiating a slot assignment algorithm to search for an alternative landing time slot based on the arrival time of the aircraft at the airport, the alternative landing time lot being an available landing time slot in a sequence of available landing time slots as close to the arrival time as possible, and assigning the alternative landing time slot to the aircraft.

The method may further comprise notifying an arrivals manager system for the airport of the assigned alternative landing time slot.

The method may further comprise receiving a confirmation from the arrivals manager system that the assigned alternative landing time slot is acceptable.

The method may further comprise relaying the assigned alternative landing time slot to the aircraft upon receipt of the confirmation. Optionally, the relaying is done using an airline operations control centre.

The method may further comprise storing the assigned alternative landing time slot in a database upon receipt of the confirmation.

Optionally, determining that the predetermined landing time slot is not compatible with an arrival time of the aircraft comprises the algorithm accessing a database storing an array of available landing time slots to determine the landing time slot as close to the arrival time as possible.

The method may further comprise receiving a notification indicating the aircraft’s arrival time at a predetermined geographical position between the origin of the aircraft and the airport.

The method may further comprise determining that the alternative landing time slot is not compatible with an arrival time of the aircraft at the airport based on the aircraft’s arrival time the predetermined geographical position.

The method may further comprise reinitiating the slot assignment algorithm to search for a second alternative landing time slot based on an arrival time of the aircraft at the airport, the second alternative landing lot being an available landing time slot in a sequence of available landing slots as close to the arrival time as possible.

A system for performing any of the steps of the aforementioned method is also disclosed.

Brief Description Of The Drawings The present application will now be described with reference to the accompanying drawings in which: Fig. 1 provides an overview of how using the system in accordance with the present teachings leads to improved landing operations at an airport; Fig. 2 provides an overview of the system architecture in accordance with the present teachings; Fig. 3 shows the designation airport as part of the system in accordance with the present teachings; Fig. 4 shows the Sign-up of an Airline, Air Traffic Control, Approach Control and Regulatory Body to the system in accordance with the present teachings; Fig. 5 shows the set up and planning of a flight using real time updates; Fig. 6 shows the preparation of a flight plan; Fig. 7 shows the booking of a landing slot for the scheduled time of arrival of the flight; Fig. 8 shows the operations that occur during Pushback, Taxi and take-off of the flight; Fig. 9 shows the calculation of a landing time slot in accordance with the present teachings; Fig. 10 shows the communication of the calculated landing time slot to the aircraft in accordance with the present teachings; Fig. 11 shows the recalculation of a landing time slot during flight in accordance with the present teachings; and Fig. 12 shows the operations involved in flight arrival.

Detailed Description Of The Drawings The present teachings achieve NO-HOLDING of aircraft above an airport through an innovative software - Global Air Traffic Management Solution (GATMS) - that has been developed by Shift Aviation. The inventors have devised an algorithm that secures an arrival landing slot - considering the many operational variables on the day - and delivers an on time (or earlier) arrival for a flight. This is a unique solution that will help alleviate a very real problem for the world’s airlines and airports.

GATMS does not replace any of the air traffic management structures currently in operation: it supplements and supports existing systems by delivering aircraft to a nominated ATC wayfinding location at a specific time. Once the aircraft reaches a nominated location at the specified time it will be given immediate clearance to land. From an airline perspective GATMS delivers its solution through existing aircraft communications protocols.

This is what we call the SMART Slot.

Referring to Figure 1, this shows a routine take off of an aircraft from an airport (Dublin in this case) in line with an assigned departure slot. This step is conventional. The flight continues as normal - cruise. However, when the aircraft approaches a specific point - "Initial Approach Fix", there is no assignment of the aircraft to a holding pattern. Rather, the aircraft can proceed to "Final Approach Fix" and then land at the arrival airport (Gatwick given as an example). In short, priority landing is given to aircraft using the GATMS system in accordance with the present teachings.

Fig. 2 provides an overview of the system in accordance with the present teachings. The GATMS module communicates with other entities such as air traffic control (ΑΜΑΝ, arrivals manager) and an airline operations control centre (OCC). The operation of this system will be described in more detail with reference to other figure.

Fig. 3 shows the designation of an airport as part of a unique GATMS Network.

Step 1.1 IATA produces listings of congested world airports on a regular basis. These listings are available on its website. The listing is updated annually by IATA and accessed on demand by Shift Aviation Solutions Ireland (SASI). 1.2 SASI will maintain a database of airlines operating between IATA congested airports. This will be updated twice per year in line with the change in airline schedules. 1.3 SASI will identify and select the appropriate airports that will be invited to become part of the GATMS Network.

Criteria for selection will be dictated by SASI commercial and operational requirements.

This Network is a unique collection of airports that will be linked through the proprietary GATMS communications system and managed by SASI utilising proprietary, exclusive and dedicated software. There is no other similar or existing linking of airports into such a Network anywhere in the world. 1.4 SASI will consult with key stakeholders (1.5; 1.6; 1.7 and 1.8) in order to promote a particular airline and/or an airport. Such consultations will become bilateral after agreement with individual stakeholders is reached. 1.5 Airports will contract to allow arriving flights that have been provided with a SMART Slot to land at the agreed time. 1.6 Air Traffic Control will contract that once a flight reaches an agreed wayfinding point at the appropriate time (SMART Slot) it will approve immediate landing. 1.7 The Stakeholder Triumvirate (Airline, Air Traffic Control and Airport) will agree that the SMART Slot calculated by SASI will form an Electronic Flight Contract ("ELCon") for an individual flight. This ELCon will be repeated as often as there are flights between the appropriate airport pairing. 1.8 While a SMART Slot does not require regulatory approval, the appropriate Regulatory Authority for the airline and airport will be included in all communication. 1.9 When all of the stakeholders have agreed on the methodology and fully understand the concept of both the "Smart Slot" and "Electronic Contract" the airport will be designated as GATMS Compliant. Accordingly, it will become part of the GATMS Network.

Fig. 4 Sign-up Airline, Air Traffic Control, Approach Control and Regulatory Body 1.9 Airport listing will have been designated as GATMS Compliant (steps 1.1 1.8) 2.1 Airline will be selected in line with the commercial and operational strategy of SASI. 2.2 The airlines route network will be made available to SASI following negotiation with the relevant airline. Prior to securing an agreement SASI will use available public information in order to complete an assessment of the airlines requirements 2.3 The Designated Airport will be included in the process that selects the airline (see section 1 for the assessment and selection process for airports). 2.4 Local and Approach Air Traffic Control will be included in the sign-up process. Part of this process will include the airline agreeing that its air traffic management information will be provided to SASI for the singular purpose of supporting the calculation and execution of the SMART Slot. 2.5 SASI will engage with the airline to negotiate commercial terms that will be covered by a separate commercial agreement. 2.6 Operational Data will be requested from the key stakeholders and provided to SASI in a format that will be specified in advance. A protocol will be agreed between all parties to ensure all supplied data is correct, appropriate, robust and shareable. 2.7 Once the required data is verified and tested it will be uploaded to the GATMS Database.

Fig. 5 Set-up and planning Real Time updates. Pre-flight Phase. 2.7 Data will have been uploaded to the GATMS Database and verified as being fit for purpose by SASI and Key Stakeholders 3.1 The airline will take the relevant data from GATMS Database and promulgate to its own internal systems. SASI will support efforts as required but this will remain a task and responsibility for the airline. 3.2 The airline will ensure that it’s relevant operational departments, including but not limited to: the Slot Desk, Flight Ops and Ops Control will have all appropriate and validated data that is pertinent to each individual flight movement. The GATMS Database will be updated in Real Time with any amends and changes. 3.3 Air Traffic Control will take the relevant data from GATMS Database and promulgate to its own internal systems. SASI will support efforts as required but this will remain a task and responsibility for ATC. 3.4 ATC will ensure that it’s relevant line departments and flow management systems, including but not limited to: the Approach Control, Arrivals Manager (ΑΜΑΝ) and Extended Arrivals Manager (X-MAN) will have all appropriate and validated data that is pertinent to each individual flight movement. The GATMS Database will be updated in Real Time with any amends and changes. 3.5 The Airport Authority will take the relevant data from GATMS Database and promulgate to its own internal systems. SASI will support efforts as required but this will remain a task and responsibility for the airport. 3.6 The Airport Authority will ensure that it’s relevant operational departments, including but not limited to: Schedules Planning, Ground Control and Parking Allocation will have all appropriate and validated data that is pertinent to each individual flight movement. The GATMS Database will be updated in Real Time with any amends and changes.

Fig. 6 Prepare flight plan inputs and output - Pre-flight Phase. 4.1 The airline produces and publishes an initial flight schedule approximately one year in advance of flight departure. There can be a number of versions before a final schedule is produced. Occasionally there can be amends to the schedule once the final version has been posted. All versions of the airlines schedule will be uploaded to the GATMS Database. 4.2 In advance of flight departure the airlines operations control department produces an initial flight plan that takes standard and known information into account with average fuel and other load weights into account. Closer to the flight an amended flight plan can be produced when known operational variables (such as weather, en-route congestion and airport minima are available. The final flight plan is posted after the flight crew sign-off prior to departure.

All versions of the flight plan will be uploaded to the GATMS Database, in addition to being posted to the systems of other stakeholders in the flight process (en-route ATC and Arrivals Airport). 4.3 The GATMS Database will judiciously select key information from the flight plan that will be used by the GATMS Algorithm to calculate the SMART Slot. This data will be amended in Real Time as updates are received by the GATMS Database. 4.4 The airline will transfer agreed flight movement and operational data to Air Traffic Control in line with normal procedure. The GATMS Database will receive updates in Real Time 4.5 The airline will transfer agreed flight movement and operational data to the arrival airport in line with normal procedure. The GATMS Database will receive updates in Real Time Fig. 7 Booking a Slot for the Scheduled Time of Arrival - Pre-flight Phase. .1 The GATMS Database will store a listing of all available slots as determined by ATC for the arrival airport. Each airport will have a unique listing of slots, referred to by SASI as the "Slot Ladder", as determined by flight separation at that airport for normal operations (flight separation will change during periods of disruption). Changes will be updated in Real Time to the GATMS Database. .2 The Slot Ladder will show the expected flights for the time period. These are generally clustered around times that are seen as ‘customer-friendly’; the marketing times, and a number of airlines may be scheduled to operate at the same time. .3 The GATMS Algorithm will separate the flight movements into departures and arrivals, in order to determine an optimum reserved slot for the airline. .4 The GATMS Algorithm will separate the flight movements into departures and arrivals, in order to determine an optimum reserved slot for the airline. .5 The GATMS Algorithm will reserve a slot for the airline at its published scheduled time. This becomes the booked slot and will be automatically processed 24 hours in advance of flight arrival. This is a unique feature that is made possible by the GATMS Algorithm. .6 When the aircraft is airborne from its departure airport it generates a message to the airline’s Operations Control Centre (OCC). This is instantly relayed to GATMS Database as a Trigger Alert and the GATMS Algorithm calculates a SMART Slot for the particular flight which is relayed to the aircraft in Real Time. .7 When the SMART Slot has been advised to the airline an Electronic Contract (ELCon) will be in place between the airline, the airport and ATC: once the aircraft reaches a nominated Wayfinding Point (WaP) at the time specified by ATC the airline will have fulfilled its part of the ELCon and ATC will advise a vectored approach to immediate landing; thereby eliminating the need for the aircraft to join a holding stack. Once the aircraft has landed the ELCon will have been fulfilled.

Fig. 8 Pushback, Taxi and take-off - Depart and Take-off Phase. 6.1 The flight will undergo all of its normal processes and procedures to effect departure. Ideally, this will be as scheduled (the STD) but if there is a delay in departure this will not have any bearing on the downstream calculation of the SMART Slot as this is activated by the Trigger Alert only when the aircraft is airborne. There is no GATMS involvement. 6.2 The aircraft will be given clearance to pushback by local ATC when all of the departure formalities are finalised. There is no GATMS involvement. 6.3 ATC will then advise the aircraft that it has clearance to taxi to the appropriate runway. There is no GATMS involvement. 6.4 ATC will then taxi. There may be a fast taxi, or some delay, depending on apron and taxiway activity. There is no GATMS involvement. 6.5 Flight takes off as normal and is monitored and directed by local ATC. There is no GATMS involvement. 6.6. When the aircraft is airborne from its departure airport it generates a flight message that is conveyed to the airline’s Operations Control Centre (OCC) via ACARS. There is no GATMS involvement. 6.7 The airline’s OCC registers the individual flight airborne time in its database. There is no GATMS involvement. 6.8 The OCC system instantly relays the airborne time to the GATMS Database as a Trigger Alert. The GATMS Algorithm then calculates a SMART Slot for the particular flight which is relayed to the aircraft in Real Time.

Fig. 9 Calculation of SMART Slot - Climb and Cruise Phase. 6.8 The OCC system instantly relays the airborne time to the GATMS Database as a Trigger Alert. This is relayed in Real Time. 7.1 The GATMS Database will have the required and Real Time data in order to calculate a SMART Slot. Once the airborne time is uploaded the GATMS Algorithm will commence the process and a SMART Slot will be calculated and relayed to the aircraft within 3 minutes (through the airline’s OCC and via ACARS). 7.2 The GATMS Algorithm will compare the airborne time to the expected airborne time and determine if the flight is operating as expected or if it is delayed. The algorithm will calculate the best possible arrival slot based on these variables in Real Time. 7.3 If the flight is NOT on time the GATMS Algorithm will consult the Slot Ladder and secure the best available slot. 7.4 If the flight is on time the GATMS Algorithm will extrapolate an arrival time taking all operational variables into account. 7.5 The Slot Ladder will have Real Time data on the available slots at the arrival airport for the period of the flight movement (see section 5). 7.6 The GATMS Algorithm will determine the best available slot that will be as close to the original booked slot as possible (see section 5). 7.7 The GATMS Algorithm will determine the earliest available slot. 7.8 If an earlier slot is not available the GATMS Algorithm will continue with the booked slot. 7.9 The GATMS Algorithm will determine the best available slot and secure this in the GATMS Database. 7.10 The earlier reserved slot (see section 5) will be secured by the GATMS Algorithm. 7.11 The best available slot will then be confirmed to the GATMS Database. 7.12 Once the best available slot has been secured in the GATMS Database it will be formally confirmed to the arrival airport A-MAN system. The GATMS Database will then be updated to reflect the slot confirmation by ATC at the arrival airport. The entire process will take 3 minutes.

Fig. 10 Communication of SMART Slot to aircraft - Climb and Cruise Phase. 8.1 The GATMS Database will have been be updated in Real Time to reflect the slot confirmation by ATC at the arrival airport. This will be relayed to the airline’s OCC as a SMART Slot.

The airline will have agreed with SASI that it’s part of the ELCon will be to reach the nominated WaP at the specified time; i.e. the SMART Slot. 8.2 The GATMS Database will relay the SMART Slot to the airline’s OCC for transmission to the aircraft. 8.3 The SMART Slot will be input to the ACARS system in line with normal airline process for updating an aircraft in flight and will comply with existing data formats and protocols. 8.4 The SMART Slot will be transferred to the aircraft in Real Time and uploading to the aircraft will be within 2 minutes from data entry. (TBC) 8.5 The pilot will receive the data inflight via the ACARS communications system. He will manually update the Flight Management System (FMS) with the SMART Slot data. 8.6 The FMS will adjust the flight variables in accordance with the SMART Slot data. This could mean speeding up, slowing down or amending a flight vector.

Fig. 11 Amendment of SMART Slot during flight - Climb and Cruise Phase. 9.1 GATMS monitors the flight progress in Real Time through the input of updates from the aircraft passing through a WaP (specific WaP’s are identified in the final flight plan). 9.2 A en-route Air Navigation Service Provider (ANSP) may instruct a flight to amend its speed, height or vectoring and this could impact the SMART Slot. 9..3 When en-route chances are advised the airlines OCC are informed in line with normal protocol. The OCC will relay any update to the GATMS Database. 9.4 The GATMS Database will be alerted via the WaP monitoring system with a secondary alert from the airline’s OCC. 9.5 GATMS Algorithm will consult the Slot Ladder to determine the options that are available for arrival slots that are consistent with the initial SMART Slot. 9.6 The GATMS Algorithm will review and determine if an earlier slot is available. 9.7 If an earlier slot is available then it will be reserved by the GATMS Algorithm. 9.8 If a suitable slot (earlier, initial reserved or original SMART Slot time) is not available then best available will be secured by the GATMS Algorithm. 9.9 The GATMS Database will confirm the new slot with the Arrivals Manager system (A-MAN). 9.10 When the amended slot has been confirmed the GATMS Database will be updated with the new (amended) slot. 9.11 The GATMS Database will advise the amended SMART Slot to the airline’s OGC. 9..12 The amended SMART Slot will be uploaded to the aircraft vis ACARS in Real Time (see section 8) and the flight variables will be will be altered in accordance with the new SMART Slot data.

Fig. 12 Flight arrival. Approach and Land Phase. .1 Once the flight has completed its cruise phase it will commence the arrival protocol. The aircraft will have passed through many WaP locations during the flight and will reach the nominated WaP that has been specified in the SMART Slot. .2 When the flight reaches the nominated WaP, Approach Control ATC determine if it has complied with the terms of the SMART Slot. .3 If the SMART Slot timings have been achieved, then Approach Control will give the aircraft an unimpeded vectored approach to the Final Approach Fix (FAF). The time lag between the WaP specified as part of the SMART Slot and landing will differ between airports and the level of flight activity on the day. However this will be the shortest duration possible and will not unduly delay arrival. .4 Once the aircraft reaches the FAF it will have a clear path to landing. .5 The aircraft landing will be monitored by the Airport Authority in line with its ELCon deliverables. .6 Once the aircraft lands the ELCon for that individual flight will deem to have been fulfilled. .7 If the SMART Slot timings have NOT been achieved, then Approach Control will determine a new landing slot for the flight. .8 The aircraft may be directed by Approach Control to enter a holding stack or take an extended vector approach as it has missed it’s SMART Slot. It will join other flights and await its turn to land, having given up its ‘priority’ status by not achieving the time associated with the SMART Slot. .9 The flight will then be given landing instructions as normal.

Glossary of terms • SASI: Shift Aviation Solutions Ireland. Organisation that has invented and is deploying the SMART Slot technology and process that is calculated by a CATMan algorithm.

• SMART Slot: Scheduled Managed Arrival Reserved Time Slot. This is the unique deliverable that is made possible by the invention and is calculated in Real Time by the GATMS Algorithm taking variable inputs from flight movements and live operational information in conjunction with historical and analytical data.

• GATMS: Global Air Traffic Management Support. This is the proprietary software that has been invented by SASI to calculate and manage the allocation of SMART Slot’s for airline customers.

• GATMS Database: Storage, processing and communications database for the SASI proprietary SMART Slot deliverable.

• GATMS Algorithm: Unique algorithm that calculates the SMART Slot for an individual flight taking Real Time information into account, including; operational, flight, weather, airport, aircraft analytical and flight crew data.

• Designated Airport: Not all airports will be designated as GATMS compliant. A Designated Airport is one that has signed-up to the GATMS process, shares relevant information and fully subscribes to the fulfilment of an Electronic Flight Contract on an individual flight basis.

• Key Stakeholders: Designated Airports, Subscribing Airlines; participating Air Traffic Control providers; key regulatory bodies.

• ELCon: Electronic Flight Contract. This is an agreement between key stakeholders that when a party achieves a deliverable the others will deliver their obligations in terms achieving a SMART Slot for the airline.

• WaP: Wayfinding Point. This is a navigational point that is determined by GPS coordinates and is used by the industry to manage and control airspace. There are many wayfinding points during the course of a flight and airlines also use these to monitor the position of an aircraft during flight.

• Final Approach Fix (FAF): This is the last wayfinding point (WaP) that an aircraft must pass before landing. Once an aircraft is at FAF then it is cleared to land.

• Slot Ladder: Availability of slot timings at an airport for a particular time period. It is a mechanism used in the GATMS Algorithm to support the calculation of a SMART Slot.

• Trigger Alert: When an aircraft becomes airborne from its departure airport it triggers an electronic alert via the airlines operations control centre that leads to the calculation and communication of a unique SMART Slot for that individual flight.

• Real Time: In the context of GATMS Real Time is defined as live, operational and may have a short time lag of less than 3 minutes.

• ACARS: Aircraft Communication Addressing and Reporting System. This is a digital datalink system for the transmission of short messages between an aircraft and its ground control station.

The words comprises/comprising when used in this specification are to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers , steps, components or groups thereof.

Claims (5)

1. A computer implemented method for allocating a landing time slot to an aircraft at an airport comprising: allocating a predetermined landing time slot to the aircraft; receiving an notification indicating the time that the aircraft departed from its origin; determining that the predetermined landing time slot is not compatible with an arrival time of the aircraft based on the time that the aircraft departed; initiating a slot assignment algorithm to search for an alternative landing time slot based on the arrival time of the aircraft at the airport, the alternative landing time lot being an available landing time slot in a sequence of available landing time slots as close to the arrival time as possible; and assigning the alternative landing time slot to the aircraft.

2. The method of claim 1 further comprising receiving a notification indicating the aircraft’s arrival time at a predetermined geographical position between the origin of the aircraft and the airport.

3. The method of claim 2 further comprising determining that the alternative landing time slot is not compatible with an arrival time of the aircraft at the airport based on the aircraft’s arrival time the predetermined geographical position.

4. The method of claim 3 further comprising reinitiating the slot assignment algorithm to search for a second alternative landing time slot based on an arrival time of the aircraft at the airport, the second alternative landing lot being an available landing time slot in a sequence of available landing slots as close to the arrival time as possible.

5. A system configured to perform the method of any one of claims 1 to 4.