Rear Admiral (ret'd) James Goldrick AO, CSC is a Nonresident Fellow at the Lowy Institute.

The unexpected arrival of a suspected illegal entry vessel (SIEV) at Geraldton last week highlighted both the difficulty of national maritime surveillance and the poor understanding of its complexity and scale.

Border Protection Command has finite resources to accomplish an enormous task and it organises those resources based on a continuing assessment of the eight designated threats to maritime security. That assessment is based on a whole range of inputs, including intelligence.

Successive governments have come to understand — sometimes the hard way — that maritime surveillance is always a matter of risk management and that greater effort in one area necessarily results in reduced activities elsewhere, unless more funding is made available.

Even if new assets are added, however, the possibility of an unexpected arrival can never be completely removed. With enough resources, the probability of detection can become very high, but it is practically impossible to force it to certainty. The law of diminishing returns comes into force — doubling the surveillance effort does not necessarily result in doubling the chance of a successful detection.

There is no 'all seeing' permanent eye over every square centimetre of ocean. In fact there is often an inverse relationship between the discrimination which can be achieved by a remote surveillance system on an uncooperative target and the 'dwell time' during which the system can remain in contact with that target. A small example of the problem can be found on Google Earth: the current satellite photo of the naval base at Garden Island in Sydney has images of old amphibious ships which were moved to other berths some six months ago.

The small wooden vessels involved in much of the illegal fishing and illegal entry activity are, due to their size, construction and lack of electronic emissions, among the most uncooperative maritime targets. And even the most primitive engine-powered boat can move something like 250km in a single day.

Furthermore, the greater the flexibility, endurance, detection ability and range over the electromagnetic spectrum that surveillance systems possess, generally the higher their cost. In these circumstances, getting the package of surveillance capabilities right has long been a concern for Australian authorities.

In addition to the support provided by Defence through the Air Force's AP-3 maritime patrol aircraft, the current civil aerial surveillance program uses specially configured DASH 8 surveillance aircraft with civilian crews.

It is important to note that when the tender for the contract for the surveillance program was issued, what was then Customs Coastwatch specified what it needed and what it could afford to spend. Responses to the tender included some very sophisticated proposals using satellites and other assets, but for the conditions and the target sets (notably the small wooden vessels) with which Coastwatch had to deal, the manned aircraft solution was clearly the most effective and best value for money.

Within the current allocation of funds, it is likely that this remains the case. The point is, while capabilities such as unmanned aerial vehicles and additional satellite imagery could add a lot, there will be significant costs involved in making such additions. Any new measures must be carefully considered and should truly 'value add' to the whole package of surveillance and response.

In the end, it must be understood that there is and can be no impervious 'ring of steel' around the Australian mainland. The task is too big and too complex for that and it probably always will be.

Photo by the Department of Defence.