When runways in use are not visible from the tower, what must be advised to the local controller?

In situations where the runways in use are not visible from the tower, it is essential to advise the local controller of the aircraft's location. This information is crucial for ensuring safe and effective air traffic management, as it allows the local controller to maintain situational awareness of aircraft movements in relation to the runways. By knowing the precise location of each aircraft, the local controller can make informed decisions regarding clearances, sequencing, and any necessary actions to prevent conflicts or incidents.

The other options, while relevant in different contexts, do not directly address the immediate need for situational awareness when visibility of the runways is compromised. For instance, knowing the type of aircraft using the runway can be useful for determining required spacing and handling characteristics, but it does not contribute as directly to the management of aircraft positions as their actual location does. Similarly, estimated time of departure is more pertinent to departure planning rather than immediate runway management, and runway condition reports, while important for safety, do not inform the local controller about the current location of aircraft.