IFATCA Policy is:

Visual observation in ATM is defined as: Observation through direct eyesight of objects situated within the line of sight of the observer possibly enhanced by binoculars.

An Aerodrome Control Tower is a unit established to provide air traffic control service to aerodrome traffic. The tower cab shall be constructed as to provide aerodrome controllers the capability to maintain a continuous watch on all flight operations on and in the vicinity of the aerodrome as well as vehicles and personnel on the manoeuvring area. Watch shall be maintained by visual observation, augmented by radar or other approved surveillance systems when available.

Before any Aerodrome Control Service Concept can be endorsed by IFATCA, the following requirements shall be met:

• The controller shall be provided with at least the same level of surveillance as currently provided by visual observation;
• The introduction of Aerodrome Control Service Concepts shall be subject to a full safety analysis and relevant safety levels shall be met;
• Contingency procedures shall be in place;
• Controllers shall be involved in the development of Aerodrome Control Service Concepts.