Pre-Departure Sequencing

A Key Element of Airport Collaborative Decision Making (A-CDM) to improve On-Time Performance

ORTHOGON Pre-Departure Sequencer

Pre-Departure Sequencing (PDS) is a core element of the Airport Collaborative Decision Making (A-CDM) concept that many airports have deployed around the world. The ORTHOGON PDS meets the requirements outlined in the Eurocontrol A-CDM Implementation Manual. Pre-Departure Sequencing optimizes flight departure planning by improving the operational predictability of the push-back process taking into account runway capacity and surface constraints as well as variable taxi times (VTT).


ORTHOGON PDS performs continuous take-off sequencing resulting in Target Start-up Approval Times (TSATs) and Target Take-off Times (TTOTs) which can be shared among all stakeholders. The ORTHOGON PDS enables reduction in taxi times, queue lengths on taxiways and runway holding times, therefore saving fuel and emissions while improving predictability of the outbound traffic even in adverse conditions.


Based on user preferences and resource constraints, the ORTHOGON PDS application enables shared situational awareness among all airport stakeholders in accordance with the A-CDM concept endorsed by Eurocontrol, ACI, IATA and CANSO.


  • A-CDM Compliance: Ensures compliance with existing and future A-CDM standards
  • Reduces influence of adverse conditions (e.g. weather, de-icing) on departure planning
  • Increases Capacity by enhanced tactical scheduling and reducing the percentage of wasted slots
  • Increases Operational Predictability and stability of the traffic flow through shared situational awareness and accurate TSAT & TTOT predictions
  • Improves On Time Performance through more accurate off block times and improved adherence to ATFM slots
  • Considerably Reduces Taxi-Out Times and Departure Queue Lengths, which Lowers Operational Costs as a result of reduced taxi times and waiting times with engines running
  • Decreases Environmental Impact due to significant reduction in CO2 and NOX emission as a result of reduced taxi times and waiting times on engines


  • Key element of Airport Collaborative Decision Making (A-CDM)
  • Basis of the extension to a Departure Manager (DMAN) as per SESAR Pilot Common Project (PCP)
  • Seamlessly integrates with existing airport systems such as the Airport Operational Database (AODB)
  • Easily configured and adopted for airports with varying levels of complexity
  • User friendly HMI (supporting touch input) built with operator inputs and validation


Airport Integration and Throughput

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Airport Collaborative Decision Making (A-CDM)

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Enabling ICAO ASBU

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"Throughout Gatwick's A-CDM 55 program, Harris Orthogon has provided a high quality product and service delivery."

Chris Howell, Head of Business Systems - Gatwick Airport IT

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