Sydney Kingsford Smith Airport, in Sydney, Australia.

What is the difference between SYD and YSSY?

SYD is the IATA code, used commercially — tickets, timetables, luggage tags. YSSY is the ICAO code, used operationally by pilots and air traffic control, and assigned geographically by region.

What airport is SYD?

SYD is

Sydney Kingsford Smith Airport

Sydney, Australia

Why the code is SYD

SYDney.

The airport authority or a contemporaneous record states this directly.

The airport

IATA code: SYD
ICAO code: YSSY
Airport: Sydney Kingsford Smith Airport
City: Sydney, Australia
Opened: 1920
Code origin: Documented

Australian ICAO codes begin with Y, which has nothing to do with Canada's Y prefix and is pure coincidence of the ICAO allocation. Sydney has a legally mandated curfew between 11 p.m. and 6 a.m., which shapes the timing of every long-haul flight into Australia.

The other code, YSSY

Every airport has two codes. The three-letter IATA code, SYD, is the one on your boarding pass and your luggage tag, and it is assigned for commercial use. The four-letter ICAO code, YSSY, is the one pilots and controllers use, and it is assigned geographically: the first letter or two identify the region, so every airport in the same part of the world shares a prefix. That is why YSSY looks nothing like SYD.

Common questions

What airport is SYD?: Sydney Kingsford Smith Airport, in Sydney, Australia.
Why is Sydney's airport called SYD?: SYDney.
What is the difference between SYD and YSSY?: SYD is the IATA code, used commercially — tickets, timetables, luggage tags. YSSY is the ICAO code, used operationally by pilots and air traffic control, and assigned geographically by region.

Australia Capital, area, population and currency
The flag of Australia Colours, symbols and lookalikes
Airport codes in Australia 2 here
What airport is MEL? Melbourne Airport, Melbourne

Sources

OurAirports — OurAirports (Public domain)

How these figures are compiled and checked