Calculated take off time (CTOT)/target time of arrival (TTA)

What problems are we addressing?

The overall ATM system suffers from a lack of understanding and predictability about when aircraft will take off and land. Because of this, margins have to be introduced into the airspace planning and management system to allow for wide variances of targeted take-off and landing times and these margins reduce the overall capacity of the system.  If we could predict, with greater accuracy, the actual take-off and landing times of aircraft we could fit more flights into the system and give airspace users greater flexibility in their choice of routes.

The programme

CTOT is a tactical slot allocation time calculated to determine the time at which a flight is required to become airborne. Target Time of Arrival (TTA) is a progressively refined planning time that is used to coordinate between arrival and departure management, and to support DCB. This solution provides a complete set of DCB measures (including Dynamic Airspace Configurations) combined with 4D constraints that are needed to optimally adapt airspace capacity to the demand and minimize demand adjustments. Integrated airspace and 4D constraint solutions are obtained through an iterative optimisation and Collaborative Decision Making (CDM) processes involving local, sub-regional and regional levels. One essential element is to ensure aircraft adhere to changes in the flight plan as a result of capacity issues which give specific target times for en-route operations; a close adherence to these target times would greatly improve the predictability of traffic forecasts, leading ANSPs to better trust network predictions and reduce the buffers they insert into their capacity plans for estimates of where aircraft will be at any given time. The impact of local changes to flight plans need to be better understood at a network level, so controllers and aircraft operators see the often negative impact on network capacity of changing individual aircraft flight plans.

Expected benefits

  • Improved information sharing,
  • Enhanced predictability,
  • Increased cost effectiveness.

Programme status

Part of SESAR Project 13.02.03, of the European Commission’s Pilot Common Project Implementing Regulation, Deployment Manager work programme and Network Manager strategic project.