RPAS background

RPAS background

What are RPAS?

The term RPAS refers to remotely piloted aircraft systems, but these aircraft are also known as unmanned aerial vehicles (UAVs). The term unmanned aircraft systems (UAS) includes not only the aircraft, but all the ground support equipment and personnel.

The term drone can be seen in news stories about military operations in the Middle East using unmanned aircraft. The aircraft flying such missions are precision weapons systems. That is not what we’re talking about when we discuss unmanned aircraft operations in civil airspace. The operations CASA approves provide many safety benefits and serve the public good.

CASA (and the international aviation regulator ICAO) refers to these as remotely piloted aircraft (RPA). This term emphasises that there is a human ‘in the loop’, controlling and overseeing the aircraft, even if that person remains on the ground.

RPA come in all shapes and sizes, from those that are as big as a 737 to some that will fit in the palm of your hand. RPA can be used for such purposes as firefighting, search and rescue, disaster relief, border patrol, weather monitoring, hurricane tracking and law enforcement.


Remotely piloted aircraft (RPA) have been around a long time. Pilotless balloons bombarded Venice during the first Italian War of Independence in 1849, and the first unmanned winged aircraft were developed as ‘aerial torpedoes’ during World War I. Radio-controlled aircraft were used as targets for training gunners in World War II, and in the 1950s Australia developed a jet-powered RPA, the Jindivik, which served as a target drone until 1997.

Remotely piloted craft are also central to space flight. The Voyager 1 space probe, has been remotely controlled continuously since 1977, and is now 19 billion km from earth and moving at 17 km per second. Other remotely controlled spacecraft have landed on Mars and Venus and flown past Mercury.

Recently, RPA have become popular, as several distinct technologies have matured.

These include:

  • The widespread civilian use of GPS (global positioning systems), following the US decision to end selective availability of the system in 2000
  • Powerful lithium-ion batteries have made small RPAs possible, particularly in conjunction with brushless electric motors
  • Development of microelectronics has made sophisticated flight control systems and lightweight sensors possible
  • Advances in robotics, which brought artificial intelligence and self-learning computer software.  Some RPAs can now analyse their previous flight paths and fly more accurately on their next pass
  • Development and commercialisation of strong lightweight materials, including carbon-fibre composites.

The result is that over a short time, an RPA industry has flourished, producing aircraft that range from helicopters a few grams in weight and centimetres across to autonomous military aircraft the size of a World War II medium bomber.

More than 650 applications for remotely piloted aircraft have been identified. Most of these can be categorised as ‘dull, dirty, dangerous and demanding,’ and are tasks that a remotely piloted aircraft can do best because it does not put its pilot at risk.

Remotely piloted aircraft are a technology whose time has come-they are a new element in aviation. The challenge is to integrate them safely with existing aircraft and conventions.

RPA bring broader issues in their wake, such as the privacy implications of having camera-equipped aircraft roaming the skies and flying over places previously protected from view.

These concerns are real, but CASA is not the body to address them. CASA’s task is to deal with safety.

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