Said control system comprises: a remote device comprising: a remote module for acquiring flight plan data, and a remote module for calculating a remote trajectory or a remote setpoint according to the flight plan data; an on-board device comprising: an on-board module for acquiring flight plan data, an on-board module for calculating an on-board trajectory or an on-board setpoint according to the data acquired by the on-board acquisition module. The remote device comprises a module for validating the trajectory which is configured to: acquire the on-board and remote trajectory or setpoint; validate or reject the on-board trajectory or setpoint according to the remote trajectory or setpoint; transmit the result of the validation to the on-board device.