British Aerospace Plc BAe 146-300 , VH-EWM

While flying a coupled instrument landing system (ILS) approach
to runway 35 at Canberra, the crew received a ground proximity
warning system (GPWS) "terrain" warning at 470 ft above ground
level. As the aircraft was in visual conditions at the time, the
crew elected to continue the approach.

The crew reported that, at the time of the warning, the aircraft
was established on the ILS glideslope and descending at 650 ft/min.
However, the T-VASIS indicated one dot low. Immediately prior to
the warning, the radio altimeter indication rapidly increased, and
then decreased, apparently triggering the warning.