Airservices Australia is upgrading Sydney Airport's instrument landing systems as part of a country-wide programme.
The first phase of the project, which was to upgrade the ILS on the southern approach to the parallel runway (34R), began in October last year, while the second phase was completed before winter this year.
The third and final stage will commence next week, with the new ILS brought into service in mid-November.
The essential safety works on the ILS on the main Sydney runway (16R/34L) will begin in 2012, after the peak Christmas period, the government agency added.
Instrument landing systems support the safe and efficient movement of air traffic into and out of the airport, particularly during low visibility and bad weather conditions, the company said.
These are being upgraded or replaced by Airservices to ensure that they are in service until 2025.
Airservices Australia provides air traffic management and related airside services to the aviation industry in the country.