In ATC, what determines the effectiveness of light gun signals?

The effectiveness of light gun signals in air traffic control is primarily determined by the clear visibility of the signals. Light gun signals are visual communications used by air traffic controllers, particularly in situations where radio communication may not be available or functional, such as when a pilot's radio is inoperative.

Clear visibility is crucial because the pilot must be able to see the signals from the controller to respond appropriately. This visibility can be affected by various factors like weather conditions, the location of the aircraft relative to the control tower, and even the quality and brightness of the light gun itself. If the signals are not clear, pilots may misinterpret them, leading to unsafe situations.

Other options like the complexity of the landing procedure, the availability of alternative communication methods, and the altitude of the aircraft do not directly impact the effectiveness of the signals themselves. While these factors can impact overall communication effectiveness, they do not influence the primary requirement for light gun signals, which is that they must be visible to effectively convey messages to pilots.