@ island airphoto
All commercial vessels are equipped with AIS (VHF transponder, which automatically transmits position reports) and SSAS (a satellite based reporting system, which can be polled), these systems are in addition to VHF and HF DSC systems.
With reference to the last position wonder if the Ozzie Jindalee OTHR system tracked this flight, provided it was switched on and operational (weekend!). Supposedly they can see and track a Cessna taking off from East Timor.