Context: Warrant Officer of the Air Force (WOFF-AF) is the most senior Warrant Officer in the Royal Australian Air Force (RAAF). It is a singular appointment -- it is only held by one person at any time. The special insignia for the WOFF-AF is the Australian coat of arms with a wreath around it. The current Warrant Officer of the Air Force is Robert Swanwick.

Question: what is a warrant officer in air force?
Steam of consciousness below:

To answer the question, consider the following: Warrant Officer of the Air Force (WOFF-AF) is the most senior Warrant Officer in the Royal Australian Air Force (RAAF).
So, the answer is the most senior Warrant Officer in the Royal Australian Air Force ( RAAF ).