The invention provides a control mechanism for controlling flight of an aircraft, the control mechanism comprising a cyclic control stick (1) that is mounted to tilt (B1, B2) on a carrier structure (4) and that is in engagement with remote mechanical transmission members (2, 3). The stick (1) is arranged as a telescopic member provided with locking means (20) for locking it in a normal-use retracted position, and is equipped with deployment means (21). Unlocking of the locking means (20) and use of the deployment means (21) depend on an assistance device (17) associated with the stick (1) being in a defective state. In the event of such a defective state being detected, the stick (1) is suitable for being deployed so as to increase the comfort of the pilot while manipulating it.