The Army has taken the unusual step of apologising in advance to Perth residents for the noise expected to be generated during month-long counter terrorism exercises.
Six black hawk helicopters have been flown in from New South Wales for the training and will be cruising the city's skies late at night, often at low altitudes.
Major Tony Cameron, from the Army's 6th Aviation Regiment, said the noise was an unfortunate side effect of the training which needed to be as realistic as possible to ensure troops were ready if the real thing ever occurred.
"We have very deliberately chosen our targets to spread the noise around... and in most occasions we will only be operating in an area for one day," he said.
"There may be one or two occasions where we will be flying around after midnight in the early hours of the morning but we have limited that as much as possible."
Elite Special Air Service troops will take part in the series of mock missions that will feature simulated explosions and gun fire.
Some of those missions will take place in the heart of the Perth CBD as well as coastal suburbs including Swanbourne and Cottesloe near Campbell Barracks.
Other exercises will also be conducted near Bindoon.
The last time Black Hawk's graced Perth's skies was nearly three years ago for the Commonwealth Heads of Government Meeting.