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Sandy Brownlee University of Stirling

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2 Outline The ground movement problem Real world data sets OSM / NATS layouts FR24 movements Handling Uncertainty Sources of uncertainty Taxi time uncertainty Possible approaches

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3 Ground movement Moving an aircraft from one point to another, in as quick and fuel-efficient way as possible, considering existing aircraft movements and route restrictions

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4 Data sets Required? Edge+node coordinates, aircraft timings No substitute for good quality data direct from airports, but freely available: potential for benchmarking OSM free to copy, distribute, transmit and adapt our data, as long as you credit OpenStreetMap and its contributors so the following are OpenStreetMap contributors Not perfect but surprisingly accurate, and can be edited to fix imperfections Export XML file taxiways and runways identified by type tags

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5 OSM - Manchester

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6 OSM - Stansted

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7 NATS AIS (Aeronautical information service) Charts and data for UK airports Includes coordinates of stands often missing from OSM

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8 Ground movement layouts Used these sources to generate layouts for Birmingham, Edinburgh, Glasgow, Manchester, Stansted happy to share if they are of use

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9 FlightRadar 24 Real-time tracking of ADS-B transponder data Lat/lon/altitude every few seconds Works for most airports in Europe + USA, plus many elsewhere Only includes approx. 50-60% of flights Somewhat noisy, needs cleaned Cant be used for example problems, but suitable for analysis of real-world movements Already used in a handful of publications

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10 FR24

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11 FR24 actual movements

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12 FR24 actual movements

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13 FR24 stand use rates

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14 Approaches to GM Mixture of routing and scheduling Numerous approaches tried, using either fixed routes or shortest paths: Mixed integer linear programming Genetic algorithm Current work is with QPPTW Based on Dijkstras algorithm find quickest path, while respecting times reserved for other aircraft Assumes that times and taxi speed estimates are correct

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15 QPPTW at Manchester Demo video

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16 Uncertainty Sources of uncertainty Off-block & pushback times Runway times Taxi speeds Runway crossings Breakdowns / blockages Weather Others Most tend to be handled by simply running the route allocation regularly with most up-to-date data

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17 Taxi time uncertainty Taxi times for individual edges are quite variable:

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18 Taxi time uncertainty Earlier work (Ravizza 2013, 2014) found taxi time estimates at Zurich to be: Can just add padding but this has an impact on taxi times too (preliminary results follow) Also variation can be cumulative Estimation accuracy % of movements% of mean taxi time of 443.5s Within 1 min63%13% Within 2 min89%27% Within 3 min97%40%

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19 Effect of adding padding Total delay (211 aircraft)

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20 Effect of adding padding

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21 Handling uncertainty: to-do Improve the modelling further Informed by more real world data Adding buffers to taxi times Better understand the trade-off between buffer size and impact on taxiway capacity A smarter approach to buffering, respecting the distribution of possible taxi times Adopting methods used in job-shop scheduling with uncertain processing times (equating processing time to edge traversal time)

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22 Summary Sources for freely-available data: Open street map NATS AIS FlightRadar24 Handling uncertainty in ground movement

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23 Thanks Any questions? Useful addresses: www.openstreetmap.org/ www.nats-uk.ead-it.com/ www.flightradar24.com www.cs.stir.ac.uk/~sbr sbr@cs.stir.ac.uk