The Air Traffic Control - Trajectory Based Operations (ATC-TBO) project proposes to validate TBO SESAR Solutions for flights in the tactical execution phase for en-route and TMA operations, thus contributing to the finalisation of the SESAR Phase C developed in SESAR 2020 and the realisation of the Digital European Sky vision in SESAR Phase D. The results are expected to contribute to capacity, operational efficiency, safety, environment and cost efficiency. The SESAR Solutions, with the TRL/EOCVM levels at the start and end of the project are: • Solution #4: Improved automation in sector planning and separation management via enhanced trajectory predictions and controller tools, including the completion of Solution 53A from SESAR 2020 to V3 (Initial = TRL4/V2; Target = TRL6/V3) • Solution #5: Improved air/ground trajectory synchronisation via lateral and vertical complex CPDLC clearances to support TBO, including completion of Solution 56 from SESAR 2020 to V3 (Initial = TRL4/V2; Target = TRL6 /V3) • Solution #6: Advanced separation management function concepts and tools, making use of more reliable trajectory information and advanced use of datalink/CPDLC (Initial = TRL1/2 (V0/V1); Target = TRL4/V2) The ATC TBO project consortium - with EUROCONTROL as the project coordinator, and steering from the PMB and the SJU - brings together 14 ANSPs, 1 airspace user, 10 airborne and ground industry partners, 5 research establishments, and 1 university. 14 EU member states, Switzerland and the UK are represented. The proposal describes 21 validation exercises including real-time simulations, fast-time simulations, and expert groups. The 'design', 'development & validation', and 'data pack & maturity gate' phases are planned for the second half of 2023, 2024, 2025 and the first half of 2026.