The invention relates to a system for opening and closing a window aperture, the system comprising: a moveable window panel; a pulley assembly coupled to the moveable window panel; a counterweight; and a pulley actuation mechanism. The moveable panel is heavier than the counterweight, the latter being attached to a first lateral side of the moveable panel via a first part of the pulley assembly. The pulley actuation mechanism is attached to an opposite lateral side of the moveable panel via a second part of the pulley assembly. The pulley actuation mechanism is switchable between energised and non-energised states based on one or more trigger events, between a closing mode whereby the pulley actuation mechanism retracts the second part of the pulley assembly thus imparting an additional closing force to the moveable panel sufficient to raise the moveable panel; and an opening mode whereby the pulley actuation mechanism is non-energised such that a passive opening force is imparted to the moveable panel by virtue of its weight to lower the moveable panel. A system for controlling a window system based on aircraft detection is also disclosed.