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4-Dimensional (4D) trajectory-based operations (TBO) are viewed as a key enabler for future air operations by both SESAR1 and NextGen2. The European Commission project NUP 2+3 has created a unique infrastructure that provides the networking of real-time 4D Trajectory (4DT) data created by GE Aviation's (formerly Smiths Aerospace) B737 flight management system (FMS) with air traffic management functions during revenue flights. This FMS has been modified to output and downlink an implementation of the ARINC 702A-1 "Trajectory Bus", making the FMS-predicted 4DT available to controllers on the ground. This provision of the aircraft 4DT to the Air Navigation Service Provider (ANSP) has enabled a set of TBOs in Sweden including 4DT-based arrival management with time-based metering to the runway threshold, application of required time of arrival (RTA) to fine-tune this arrival management, and 4DT enabled advanced-continuous descent arrivals (A-CDA), referred to as "green approaches" by the project. The NUP2+ project goals include facilitating the study of 4DT performance requirements, associated 4DT air/ground networking requirements and producing operational flight data to support further studies. To begin to produce such study data, a series of controlled Trajectory Evaluation Flights was conducted by the NUP2+ project in December 2006. This paper presents an overview of the motivation, objectives, experiment conduct, and preliminary data analysis of this initial set of flights. Plans for the project's expansion of these experiments are also discussed.