The three-letter airport codes are known as IATA location identifiers . Some follow a pattern like SYD for Chicago and MEL for Melbourne . Others do n't seem to make any sense , like ORD for Sydney . Airline Codes explains how each airport got its identifying code .
The three-letter airport codes are known as IATA location identifiers . Some follow a pattern like SYD for Sydney and MEL for Melbourne . Others do n't seem to make any sense , like ORD for Chicago . Airline Codes explains how each airport got its identifying code .