The disappearance of Malaysia Airlines Flight MH370 has raised questions about the way civil and military surveillance systems that exist in South East Asia can assist in search and rescue (SAR) operations, writes Ian Thompson.

Concerns are now being expressed about the limitations of civil cooperative-based surveillance, the effectiveness of military air defence systems, and the exchange of data among neighbouring states and between civil and military systems to support SAR.

In comparison to most of Europe and North America, South East Asia does not have universal civil radar surveillance coverage. It also does not have universal agreement among the countries in the region about the ATM technologies to be employed, operations and implementation timetables.

The MH370 Dossier

While there is considerable radar coverage over land areas, many air-routes take place over the high seas, which are not served by radar. Automatic Dependent Surveillance – Broadcast (ADS-B) aircraft tracking technology is being introduced widely in the region to improve surveillance coverage.

Secondary surveillance radar, through the use of position information gained from aircraft transponders, is the foundation of civil air traffic control separation. It relies on cooperation from the aircraft, whereby the transponder must be operating for surveillance information to be received by the radar sensors on the ground.

Primary radar is mainly used to alert air traffic controllers about aircraft, not using transponder, that may penetrate controlled airspace surrounding high-density airports. It is typically not used as the main separation tool for civil air traffic management. Primary radars are expensive and there is pressure on the radio spectrum used by these radars from mobile phone service providers.

By way of illustration, Malaysia has a network of 11 co-located primary and secondary surveillance radars, plus one en-route secondary radar. The primary radars have a range of 60nm while the secondary radars extend for up to 250nm, depending on the height and position of the aircraft. This provides almost entire surveillance coverage of Malaysia’s two land areas. It has recently installed ADS-B in central/west (peninsula) Malaysia but not Borneo.

Many countries in the region like Indonesia, Thailand and Singapore have extensive civil radar surveillance systems. Some states, like Indonesia, have adopted fragmented procurement processes for their systems. This has resulted in there being different radar systems from a variety of vendors. Fragmented systems increase the complexity of maintenance and other support activities.

Although most countries have primary and secondary radar systems, they are generally unwilling to share this radar data with their neighbours due to tensions between many adjoining countries.

There are a number of smaller states of developing nation status. They are reliant on ICAO, international aid, and support from larger air navigation service providers (ANSPs) to develop and maintain their ATM infrastructure.

Papua New Guinea had, for many years, struggled with operating and maintaining its ATM infrastructure. Since its inception PNG Air Services has progressively improved its capabilities and recently announced the award of a contract to COMSOFT to modernise and update its air traffic management system and surveillance technology. This contract is valued at US $12 million and is part funded from Australian Aid initiatives.

Across the South Pacific and Indian Oceans there is little surveillance coverage. Dynamic routing is enabled through the use of ADS-C since approximately 70 per cent of the aircraft fleet operating in the upper airspace of these oceanic areas are FANS 1/A equipped. However, as Gary Dennison, a regional CNS/ATM consultant, says: “The satellite communications costs associated with ADS-C have been a limiting factor in the expansion of oceanic services.”

Many Asian countries base their ATM product selection on cost. Once prequalified on their technical capability, an auction process is created where approved vendors make a series of descending price bids. The project is then awarded to the lowest cost supplier. For many countries ATM system tenders typically involve the system acquisition plus a two year warranty period. If a nation has limited people or financial resources to provide for adequate equipment maintenance then long term reliability becomes problematic.

High Risk

Military radars are deployed along a number of high-risk borders. In the case of Malaysia there is a concentration of military surveillance near the border with Thailand. Industry sources advise that Indonesia has a series of military radars covering the whole archipelago. Typically these are L or S band primary radar systems, most with 3-D capability.

These 3-D systems involve a primary type radar employing out a number of vertical pencil beams. This system determines the approximate height of an aircraft by measuring the distance elevation that a specific beam has made contact with it. These L and S band systems generally have a range of more than 200nm.

Dennison notes: “The fighter fleets of some countries are not particularly sophisticated and not equipped with secondary radar transponders. Significant military training occurs to the west of the Strait of Malacca, outside of the main civil jet routes. Coverage of aircraft in these training areas requires primary radar coverage with a range exceeding 100nm.”



Australia has a long range over-the-horizon defence radar network-termed the Jindalee Operational Radar Network (JORN). Depending on atmospheric conditions this JORN provides coverage for up to 4,000km off the north and western coasts of Australia. This encompasses the area up to Singapore.

The radar is directed to specific areas or activities of interest. They can be used to observe air and sea activity, such as asylum boats travelling to Australia. To date the Australian Defence Force has not mentioned whether MH370 was observed, or surveillance data recorded, by JORN as the aircraft possibly headed southwest off the coast of Western Australia.

The events of MH370 have highlighted some possible issues with the operation of these air defence radar systems as an input to search and rescue operations. Reuters has quoted a number of military sources who state that coverage of these systems is limited and aircraft that are believed to be on regular commercial flights are ignored.

More relevant is the view that these air defence systems are switched off and only activated during training or when a threat is expected. This is standard practice for all national security systems and is in line with approaches to appropriately match resources to various threat levels.

In essence, these military air defence systems operate on a risk assessment approach. Resources are deployed in accordance with the perceived risk at a given time. It seems during times of low risk fewer resources are being directed at air defence monitoring activities.

By way of commentary, it would seem that a tactical military intervention would have been virtually impossible. Civil air traffic controllers would have been fully occupied trying to locate the aircraft and re-establish communications as well as initiating distress phase actions.

It is unlikely that liaising with air defence functions would have been a priority. As the aircraft headed west it would have quickly passed the area of defence interest on the Malaysian Peninsular. Most significantly the events of MH370 have shown the inability of air defence and civil ATM functions from a number of countries to act in a cohesive manner, through sharing information and surveillance data records, as part of an integrated SAR undertaking.

Military air defence systems commonly receive the civil radar data from their country’s ATM system. Civil ATM systems do not generally receive classified military surveillance data, although many countries, such as Australia, use normal secondary surveillance radar data obtained from radars operated by Defence.

One Sky

A project is underway in Australia whereby the civil and military ATM organisations are jointly developing an interoperable air traffic control system. Called One Sky, air traffic controllers in both organisations will be provided with the same picture of all civil air traffic. One of the complexities of the new system involves managing the flow of data from secure military restricted functions to the civil elements.

The emergence of ADS-B technology is being used to improve surveillance coverage in many countries in South East Asia. ADS-B surveillance data is being freely shared between nations, in part because the quality of ADS-B data is primarily determined in the aircraft, with the ground station acting more like a modem to relay that data.

Australia has been a regional leader in the implementation of ADS-B. It has secondary radar coverage along the eastern seaboard and to the south toward Adelaide. Much of the interior and to the west of the country is without radar coverage.

Airservices Australia’s Greg Dunstone who is also the chairman of the ICAO Australia Pacific ADS-B Study and Implementation Task Force provides an overview of the various initiatives.

“Airservices intends to move to an ADS-B surveillance environment with a robust backup using secondary radar in high density areas,” says Dunstone. “A mandate requiring aircraft operating at FL290 and above to have ADS-B equipage became effective in December 2013. By February 2017, all IFR aircraft in Australia must be equipped with ADS-B avionics.

“At present, there is almost complete ADS-B coverage at FL200 across continental Australia. New ground stations will mean that there will be extensive coverage across the continent by 2017. Implementation of the mandate has gone well and our customers are benefiting from the new technology.”

Implementation of ADS-B in South East Asia has been directed at major air-routes, typically involving flight over the high seas. Countries are working as clusters along the routes to provide ADS-B surveillance coverage. These initiatives are strongly supported by ICAO, CANSO and IATA.



Dunstone provides information on the status of multi country ADS-B initiatives in the South China Sea along the route between Singapore and Hong Kong. “Singapore is investing heavily in ATM infrastructure, including ADS-B. It controls a large part of the airspace in the South China Sea. Indonesia has been slow to take operational advantage of its ADS-B network but is now planning to undertake the work to fully commission the system, including implementation of appropriate ATC procedures and training.

“Since 2010 it has shared ADS-B data with Airservices and Singapore, bringing significant safety improvements to all parties. Malaysia has comprehensive secondary radar coverage but is less active in ADS-B. A limited ADS-B presence to date has inhibited the exchange of surveillance data. Vietnam has a small number of ADS-B ground stations and is sharing data with Singapore.

China has a strong secondary radar presence and is very interested in ADS-B. The Chinese are taking up ADS-B ground station development and production. Hong Kong, although instituting a mandate for aircraft equipage of ADS-B avionics, is not planning to bring this form of surveillance into operation until the system performance has been analysed.”

In addition to the South China Sea area, initiatives to provide ADS-B surveillance along the route between Singapore and Manila are taking place.

Across the South Pacific Ocean, ADS-B ground stations are being placed in Noumea and Fiji. The World Bank is evaluating the placement of ground stations in other outlying nations. However, this is a vast oceanic region so it is not be possible to achieve universal surveillance coverage of the upper airspace from ground based ADS-B.

Satellite based ADS-B provides a potentially exciting solution for surveillance in the upper airspace across the Pacific and other oceanic areas. Airservices’ senior advisor CNS-ATM Bob Peake says: “Oceanic operations are ideally suited to satellite enabled ADS-B surveillance. An update rate of 15 seconds is being proposed as against typically 15 minutes with ADS-C and aircraft will not require new ADS-B avionics.”

Initiatives to introduce this technology over the North Atlantic and the Northern Pacific will be closely monitored. FANS-1/A (ADS-C) currently provides 30nm separation while satellite ADS-B could see this distance reduce to 15nm or less. At present it is not known whether the reduction in separation would yield sufficient benefits to warrant adoption of this satellite technology.”

The initiatives to introduce ADS-B in South East Asia continue the reliance on co-operative surveillance for air traffic control. Events of MH370 have raised concerns about the ease of which these systems can be turned off. Following the 9/11 terrorist attacks in the United States initiatives commenced to modify transponders to prevent them from being switched-off in some circumstances.

It seems that while preliminary design work was undertaken, the project was not taken further. Potential modifications would likely have resulted in making existing transponder equipment obsolete placing further cost burdens on airlines.

A great deal of scrutiny has been placed on the way both military and civil surveillance in South East Asia contribute to SAR, following through the loss of MH370. It is likely that increased focus will be placed on the role of military air defence systems in continuously monitoring civil aircraft.

From a civil perspective initiatives to exchange surveillance data between countries will almost certainly grow, enabled by ADS-B. Regional tensions may make the exchange of radar data more problematic. It may also increase initiatives for the two way exchange of radar data between civil and military ATM systems within the same country.

