Restricted airspace over the Murchison Radio Observatory

The CSIRO is seeking feedback on a proposal to establish a restricted airspace (hereafter referred to as R-MRO) over the Inyarrimanha Ilgari Bundara, the CSIRO Murchison Radio-astronomy Observatory (the Observatory).

The Observatory hosts several radio astronomy telescopes with extremely sensitive passive radio receivers. These observe in frequency ranges which are affected by licensed transmitters in use aboard aircraft, as well as by the inadvertent use of passenger or pilot mobile devices. The telescope facilities comprise Australian owned and operated facilities, representing significant investments of order several hundred million dollars, as well as the first international mega-science project hosted in Australia, the low frequency component of the Square Kilometre Array (SKA-low). Together, these projects represent an investment well above $1 billion and are of national significance.

The Commonwealth Government has supported the establishment of this facility through regulatory constraints on radio emissions by establishing a Radio Quiet Zone (RQZ), regulating the installation of permanent radio transmitters within a range of 270km of the site, and limiting the use of radio transmitters and electronic devices in general within 70km of the innermost core of the site. The Western Australian government has also provided support through limits on mining activities in the region, the negotiation of a lease over Boolardy pastoral station, and numerous other measures.

The predominant reason for building radio astronomy telescopes as far away from civilisation as possible is to minimise the impact of everyday technology. This impact is called radio frequency interference (RFI) and is caused by incidental emission from every electronic device from power tools to washing machines. RFI is particularly strong from intentional transmitters such as mobile phones and tablets, baby monitors, automotive radars, wireless keys and many more. Amongst those, some of the strongest sources of RFI include airborne transmitters such as Automatic Dependent Surveillance Broadcast Transponders (ADS-B) and distance measuring equipment. These specific transmitters in fact can be strong enough to render observations useless and can even cause damage to the radio astronomy receiver systems when approaching within a few kilometres of the antennas.

Airborne RFI erodes the painstakingly negotiated protections afforded by the RQZ and degrades the radio quiet quality of the Observatory. It also has been observed to increase in the past decade. To protect the significant investment in these facilities, CSIRO seek to keep air traffic at an arm’s length from this sensitive site.

The proposed restricted air space, R-MRO, is centred at latitude/longitude S 26.7409 / E 116.7269, is circular in shape with a radius of 62.1 km / 33.5 n mile and features a vertical extent SFC - FL600.

The existing waypoint SCRUB is removed and replaced by two waypoints set outside R-MRO, serving as new navigation points to guide airways Y15, Y44, Y60, L514 and W394 around R-MRO:

• The QUIET waypoint, placed on a bearing of 274 degrees and 72.1km from the centre of R-MRO (west of SCRUB) at WGS84 coordinates S 26.6937 E 116.0042. This provides transiting traffic on airways Y44 and Y15 a minimal avoidance option.
• The SKIES waypoint, placed on a bearing of 114 degrees and 72.1km from the centre of R-MRO (southeast of SCRUB) at WGS84 coordinates S 27.004 E 117.3905. This provides transiting traffic on airways W394, Y44 and Y60 a minimal avoidance option.

Traffic on airway L514 can pick either QUIET or SKIES for a roughly equal avoidance distance around R-MRO.

Analysis of 5 years of air traffic flying across the site shows that current regular passenger transport (RPT) traffic would be minimally affected with equivalent still air distances (ESADs) on the routes travelled increased by no more than 1.6%.

Some operators will require entry to R-MRO. The managing agency will issue standing entry permits for the R-MRO area to the following entities:

• the fly-in, fly-out (FIFO) operators flying observatory personnel and contractors into Boolardy Aircraft Landing Area (ALA) (located several km inside the R Area but well away from the sensitive infrastructure)
• the Royal Flying Doctors Service (RFDS) for purposes of tending to medical incidents requiring landing at Boolardy ALA, MRO Emergency ALA, and SKA Emergency ALA
• pastoralists affected by R-MRO that would otherwise be unable to operate their aircraft
• pastoralists for the purposes of aerial mustering.

In addition to these standing entry permits, short term entry permits can be granted to aircraft operators by the managing agency, in a process similar to CSIRO’s Radio Emissions Management Plans (REMPs) required for activities on the ground within the RQZ.

Each of the exempted airspace users will be provided with a briefing package containing:

• a detailed map of the most sensitive areas contained within R-MRO that critically must be avoided to prevent damage to the receiver systems
• contact details to coordinate their arrivals and departures
• approach and departure corridors that are safe to operate in.

Granting of an exemption to enter R-MRO will be subject to acceptance of the detailed rules set forth in the briefing package provided by the managing agency.

The managing agency for R-MRO will be the site entity group at CSIRO responsible for the management of the Observatory, known as the MRO Site Entity.

Further details and a full analysis of the impact on existing airspace users can be found in the attached document located below.