Transition Altitude (Australia)

The transition altitude in Australia is 10,000 ft — the altitude at and below which a pilot sets the altimeter to the local area QNH (the pressure setting that shows height above mean sea level), and above which the altimeter is set to the standard pressure setting of 1013.2 hPa. Above the transition altitude, vertical position is described in flight levels rather than feet AMSL.

This convention ensures that all aircraft flying at or above the transition altitude reference the same pressure datum, so vertical separation between them is meaningful regardless of local surface pressure, while aircraft closer to the ground use a setting referenced to actual terrain height.

The transition level — the lowest usable flight level above the transition altitude — varies with the current QNH and is published in NAIPS briefings; confusing transition altitude with transition level, or applying the wrong setting on climb or descent through it, is a common exam trap in CASA meteorology and air law questions.