What is the main goal of using light signals in air traffic control?

The primary goal of using light signals in air traffic control is to serve as a backup for radio communication. Light signals provide an alternative method of communication that can be utilized in situations where radio contact may not be possible, such as in instances of radio failure, interference, or within communications blackouts. The use of light signals ensures that pilots can still receive critical instructions and guidance from air traffic controllers, thereby maintaining safety and operational efficiency in the airspace.

This method of communication becomes particularly crucial at airports, especially during conditions of low visibility or when dealing with aircraft that may not have radio capabilities. Although other options suggest purposes like issuing clearances or guiding for landing, light signals are fundamentally designed as a reliable means of conveying instructions when other methods fail, reinforcing their role as a safety measure in air traffic management.