Yeah the one here isn't armed 100% of the time. But it's held here with everything it needs just incase of an emergancy, Like if a high profile flight is coming in they deploy it as a care package for said flight (and they can't get one from Williamtown). I hear that they want to have a landing strip @ JOC intime for the F35 Lightning Launch, as the F/A-18 is due to be decommisioned soon.
Edit: the one here i believe they rotate from Williamtown i don't know if it is the same plane all the time. But i see 1 at least 1 time a week.