In the Country Fire Authority (CFA) and Metropolitan Fire and Emergency Services Brigade (MFB) Melbourne, Australia, a station officer has one impeller, and a senior station officer has two impellers.
Although variations still occur at the SO level within the different state fire and rescue services due to competency, experience and qualification requirements, the Australasian Fire and Emergency Services Authorities Council (AFAC) has ensured that at the senior SO level the requirements across Australasia are generally consistent throughout all jurisdictions.
In some states systems, senior SOs can also in rural and semi-rural environments play a mentoring role across and for a diverse range of career/permanent, auxiliary/retained and volunteer firefighting personnel.
The rank badge is two impellers; they also wear a white helmet with a half-inch black band around it.
Station officers (two impeller rank marking) became watch managers.
In the United States, "station officer" is often a general term and has several meanings.