to the Data Link, it should be possible for the ground control to receive data from this on-board TP. Unfortunately, today, this promising technology is not implemented in all aircrafts. Moreover, a decision support tool requires the capacity to efficiently generate ’what-if’ scenarios. Today, it is unrealistic to receive many trajectories from the on-board system of every aircraft in the airspace and merge them into different airspace scenarios in real-time. Therefore, the ground TP is still an essential component of the future air traffic control systems.

A trajectory can roughly be separated in three phases: climbing, level flight, and descent. Phases with altitude changes are the most difficult to handle due to the differences of aircraft performances and the effect of the weather conditions. Operationally, the controllers of approach control centers, who deal with climbing and descent phases, must have a good representation of the vertical evolution of the aircraft to ensure their separations. In most airspace, this separation shall be at least 10 flight levels. For these reasons, this study will focus mainly on the prediction in the vertical axis.

The paper is organized as follows: Section \[sec:relatedWork\] surveys some recent works in the domain of trajectory prediction. Section 