Which visual aid provides information that cannot be seen from the control tower?

Information signs serve to provide crucial details that may not be visible from the control tower, such as the locations of taxiways, runways, and specific areas of interest within the airport. These signs offer guidance to pilots and vehicle operators by conveying important information about the airport layout and operational procedures.

Unlike taxiway markings, which are primarily for use on the runway or taxiway surface and can be seen by those on the ground, information signs are placed in strategic locations throughout the airport to offer context that the tower may not have a direct line of sight to. Runway lights and stop bars are also important for navigation and safety, but they function within a limited scope and do not communicate as much situational information about the airport infrastructure as information signs do. Thus, information signs uniquely fulfill the role of conveying information that enhances situational awareness for operational personnel and pilots, beyond what can be discerned from the control tower view.