The Signal Lamp, for making visual signals to aircraft, is still a feature of every Control Tower. These modern descendants of the old Aldis Lamp are generally only used in case of radio failures, although occasionally student pilots will practice 'no radio' circuit operations controlled by the Signal Lamp. The 240V lamps are normally kept on a retractable cable mounted on the ceiling of the Tower. However, the new generation of Towers being built by Airservices Australia (2010 onwards) has battery-powered lamps kept in a 'holster' on the modular workstations of these Towers.
This photo shows Air Traffic Controller Lara Baker using the Signal Lamp at Adelaide/Parafield on 20 May 2010. An inbound Cessna 210 had squawked 'radio failure' (7600) and was being processed into the Parafield circuit for a landing.
(Photo: Phil Vabre)