| Tutorials home | Decreasing risk exposure | Safety tour | Emergencies | Meteorology | Flight Theory | Communications | Builders guide |


Fly safe! home page

Australian airspace regulations


Rev. 72 — page last updated 25 July 2014
Flight Planning and Navigation
  
Google logo

Content


World-wide civil aviation must, of necessity, rank as one of the most highly regulated activities. To facilitate safe, orderly use of airspace there are two internationally agreed sets of flight rules — to which all airspace users must adhere — plus several classes of controlled airspace in which aircraft may operate to take advantage of the implied safety within that airspace. However, much of the Australian airspace below 18 000 feet above mean sea level [amsl] is classified as Class G and not controlled. This airspace is where powered recreational aviation aircraft generally operate.

Controlled means that the airspace is monitored and most traffic is directed, to varying extents, by ground-based air traffic control [ATC] specialists; and air routes are designated by ground-based radio navigation aids or by satellite-based systems.

1.1 Controlled airspace

'Controlled airspace' is airspace of defined dimensions within which air traffic control service is provided in accordance with the airspace classification. There are two types of controlled airspace:
  • A Control Area [CTA] is controlled airspace that extends from a specified limit above the surface (e.g. 8500 feet amsl) to some upper level (e.g. 18 000 feet amsl — or FL180).

  • A Control Zone [CTR] is controlled airspace, surrounding a civil or military aerodrome (with a manned Air Traffic Control tower), that extends from ground level and is stepped up to the lower limit of the overlying CTA. The steps provide the airspace for the airport approach and departure paths.

Please note: the CTA abbreviation is commonly used when referring to the generic controlled airspace (i.e. CTA plus CTR) rather than just Control Area(s). There is no abbreviation listed in the Australian Aeronautical Information Publication [AIP] for the generic 'controlled airspace'. OCTA is the AIP abbreviation for the term 'outside control area' and OCTR is the abbreviation for the term 'outside control zone'. However the OCTA term is commonly used by pilots and Air Traffic Services personnel when referring to operations outside controlled airspace.
Airspace classification
Four of the International Civil Aviation Organization [ICAO] controlled airspace classes are currently used in Australia; A,C, D and E.

Recreational Pilot Certificate holders flying an aircraft operating under the CAO 95.55, CAO 95.32, CAO 95.12 and CAO 95.10 exemption orders may only enter and fly in Class C and D airspace if they meet specified requirements; see 'Operating airspace allowed, pilot qualifications and equipment required'. For flight in Class A airspace, a recreational pilot must seek and receive written permission from the Civil Aviation Safety Authority for the flight.

It is solely the pilot's responsibility to operate legally; even obtaining an air traffic controller's permission to enter controlled airspace does not make the flight legal, nor does it absolve the pilot if something goes wrong. It is always the VFR pilot's responsibility to see and avoid other traffic.

Airspace diagram
In Australia, Class A is high-level en route airspace, and Class C surrounds major city airports and military airfields starting at ground level and stepped up into mid-level Class C or the high-level Class A airspace.

Also, when active, military restricted areas are Class C controlled airspace.

The control area — generally within secondary surveillance radar [SSR] coverage — between Sydney and Melbourne is designated Class E between 8500 feet amsl and FL125, Class C between FL125 and FL180, and Class A above FL180.



Airspace diagram
The control area — generally within SSR coverage — between Sydney and Cairns is designated Class E between 8500 feet and FL180, and Class A above FL180.

(For explanation of the 'CTAF' and '126.7' aerodrome notations appearing in the diagrams see Operations at non-controlled aerodromes and airstrips in Class G.)



Airspace diagram
CTRs at smaller regional airports (which lack primary radar coverage) are Class D airspace; these are only active as such when the control tower at that CTR is manned. They revert to Class G CTAFs at the times when the tower is not manned.

The CTR starts at the surface and is stepped up into the Class C approach/departure areas for that or neighbouring towered aerodromes. The upper boundary of Class D is generally between 2500 feet and 4500 feet amsl. Transponders are not required in Class D CTRs.

In Australia, there are six major city aerodromes (Jandakot, Parafield, Moorabbin, Camden, Bankstown and Archerfield) dedicated to general aviation purposes (i.e. no regular public transport [RPT] operations). They were formerly designated as General Aviation Aerodrome Procedure [GAAP] control zones but, in accordance with the national airspace policy, Airservices Australia implemented revised Class D air traffic procedures at those aerodromes on 3 June 2010. Thus, the 'GAAP' designation disappeared from Australian aviation regulations and airspace terms now generally conform with the ICAO standards.
Class E airspace
Australian Class E is mid-level en route airspace, the general base of which is at 8500 feet amsl within SSR coverage and at FL180 in the remaining continental area. However, there are three Class E corridors with the base at FL125 and extending up to the overlying Class A. All aircraft require a clearance from ATC before entering Class A, B and C airspace, and a transponder must be operated. VHF radio-equipped VFR aircraft (including RA-Aus/HGFA/ASRA aircraft) may operate in Class E airspace without an Air Traffic clearance, but the pilot must: In addition, the aircraft altimeter should be accurate to within 100 feet. There is a general transponder exemption (AIP GEN 1.5 para 6.1.2) for aircraft not equipped with an engine-driven electrical system capable of continuously powering a transponder. Some specific transponder exemption conditions may be allowed subject to prior agreement with ATC; see AIP GEN 1.5 para 6.2.2.

RA-Aus/HGFA/ASRA aircraft operating in Class E must be equipped with a serviceable VHF communications system. The AIP Book is perhaps at variance with the CARs and CAOs, so it is not absolutely clear whether a hand-held unit is acceptable in controlled airspace. Hand-held transceivers approved by the Australian Communications and Media Authority are acceptable for use in RA-Aus/HGFA/ASRA registered aircraft operating in Class G airspace. See AIP GEN section 1.5 paragraphs 1.1, 1.2 and 1.5.


The pinkish tinge covering most of the continent in the image below indicates the general FL180 Class E base, the tan colour indicates the areas within radar coverage where the Class E base is either at 8500 feet or FL125, and the green colour indicates where the Class E does not exist (i.e. Class C CTRs extend up to the base of Class A airspace) or Class C extends to the upper level of a Class D CTR.

Class E Airspace diagram In Class E, all flights operating under the instrument flight rules [IFR] are provided with an air traffic control separation service; hence, it is controlled airspace even though VFR flights within the same airspace are not provided with a traffic separation service — though they may be provided with a Surveillance Information Service [SIS] on request if the controllers have the capacity to do so. However, "due to the nature and type of radar coverage (in Class E), not all aircraft will be observed on radar". An aircraft operating under the VFR that encounters instrument meteorological conditions must then obtain a clearance to continue the flight under the IFR.

1.2 Airservices Australia and the Civil Aviation Safety Authority

Airservices Australia [AsA]
AsA is a government-owned corporation providing air traffic management and control together with related services within the Australian aviation industry. This includes airspace management, aeronautical information, communications, radio navigation aids plus airport rescue and fire fighting services.

Air traffic services [ATS] are provided by the air traffic controllers of Airservices Australia [AsA], using their HF and VHF radiocommunications networks or their data uplink facilities. There are two main ATS centres; Brisbane Centre [BN CEN] holds international responsibility for a flight information region [Brisbane FIR] covering the northern part of Australia plus the oceanic airspace to the east while Melbourne Centre [ML CEN] is responsible for the flight information region [Melbourne FIR] covering the southern part of Australia plus Southern Ocean and Indian Ocean airspace. Those two FIRs make up the Australian FIR covering 50 million square kilometres — about 10% of the Earth's surface.

BN CEN and ML CEN air traffic controllers and area radar controllers provide the area control service for the en route traffic. Approach controllers and approach radar controllers — plus aerodrome controllers associated with the 28 civilian international, domestic and regional towered airports — manage the terminal area traffic. There are also two 'joint-user' airport towers (Darwin and Townsville) manned by RAAF personnel.

In Australia, the assistance provided to sport and recreational aviation by ATS consists of a flight information service [FIS] — both preflight and in-flight — for traffic in the Class G and Class E airspace and an in-flight emergency response service including a search and rescue authority alerting service. The in-flight FIS consists of an ATC initiated FIS, automated broadcast services together with an ATC 'on-request' assistance service with the generic call-sign 'Flightwatch'. Standard information delivered by Flightwatch includes aerodrome weather and NOTAM.

A Surveillance Information Service [SIS] (previously known as the Radar/ADS-B Information Service [RIS]) including 'ATC flight following' may be available in any Class G and Class E airspace that is within the ATS radar surveillance coverage near the major cities, but availability is dependent on the controller's work load. If available SIS 'flight following' is of great value to transponder-equipped recreational aircraft threading their way around a control zone — thereby avoiding any unintentional violation of controlled airspace. Navigation assistance, position information and traffic information services may be provided.

ATC also provides the SARWATCH search and rescue alerting service; primarily for aircraft operating under the instrument flight rules but also automatically provided to recreational aircraft in two-way communication with ATC and operating under an airways clearance. The Airservices Australia communications network delivers air-ground-air communications to individual ATS operating positions using around 600 radio transceivers located at more than 150 sites across Australia. Remote radar, VHF and HF transceivers are linked to ML CEN and BN CEN by about 110 satellite ground stations plus microwave radio bearer links and fibre-optic link facilities. The FIR work load from 'en route' aircraft is apportioned among the FIR personnel by dividing the region into multiple 'Flight Information Areas [FIA], each FIA using a particular VHF frequency. Each air traffic controller may monitor several frequencies. Communications with aircraft in the vicinity of the major airports may be handled by operators in terminal control units such as 'Sydney approach'.
The Civil Aviation Safety Authority [CASA]
CASA is an independent statutory authority whose mission is to 'enhance and promote aviation safety through effective regulation and by encouraging the wider aviation community to embrace and deliver higher standards of safety'. CASA is responsible for safety regulations, licensing of pilots and aviation engineers, certification of aircraft and aircraft operators, and certification and registration of aerodromes.

Back to top

1.3 Class G non-controlled airspace

In Australia, all airspace that is not promulgated as class A, C, D, E or restricted is Class G, and is open for flight up to, but not including, 10 000 feet amsl to all holders of a valid Pilot Certificate flying any RA-Aus/HGFA/ASRA registered aircraft. Flight at or above 5000 feet requires VHF radio. Class G extends over most of Australia from surface level to the overlying CTA base at 8500 feet amsl, FL125 or FL180. The total volume of Class G airspace included between the average land mass elevation of 1100 feet and 10 000 feet is some 20 million cubic kilometres.
  • All sport and recreational powered aircraft operating at or above 10 000 feet amsl, whether in controlled airspace or Class G airspace, must have written CASA approval for the flight and must be equipped with an operating Mode A/C or S transponder. Also Australian Civil Aviation Order part 20.4 specifies use of supplemental oxygen systems.
Operations at non-controlled aerodromes and landing areas in Class G
Most of the roughly 2000 (excluding 'home' strips) Australian aerodromes and landing areas are in Class G airspace and have no air traffic control service; i.e. they are 'non-controlled'. To maintain safe separation in the vicinity of such airfields, pilots are required to exercise 'see and avoid' techniques supplemented by VHF monitoring and particular radiotelephony communications and procedures in Class G airspace. These are designed to maintain traffic awareness and to self-administer circuit priorities, where appropriate, in the vicinity of the airfields. Discrete radio frequencies known as common traffic advisory frequencies [CTAFs] are generally assigned for use in those circumstances — that class of airfields then tend to be known as 'CTAFs'.

Carriage and use of VHF radio transceivers is generally not mandatory — but highly recommended. However, there are about 300 certified, registered or military non-controlled aerodromes — usually those which have regular or perhaps occasional RPT movements — where the carriage and use of VHF radio, confirmed to be functioning on the CTAF, is mandatory for all aircraft (including recreational aircraft) operating at that aerodrome. That type of mandatory radio location was previously known as 'CTAF (R)' but the CTAF (R) term disappeared from the regulations 3 June 2010.

The VHF radio communications recommended when operating in the vicinity of non-controlled aerodromes are defined in the AIP Book section ENR 1.1 sections 40–50 "Operations in Class G airspace". All radio-equipped (whether fixed installation or hand-held) aircraft, including recreational aircraft, should make the one mandatory broadcast plus the recommended broadcasts, when appropriate, on the CTAF. Some non-controlled aerodromes may have a private ground-based Unicom communications operator.

Back to top

1.4 Restricted, danger and aerial sporting areas

Special use airspace, extending to varying heights, is defined on the charts used for air navigation. For safety reasons, flight into those defined special use areas may be prohibited (P), restricted (R) or marked 'danger' (D); the latter as a warning to take extra care if entering the area. Flight within a prohibited area is forbidden at all times but usually (except for Pine Gap in central Australia) prohibited areas are of a temporary nature.

Most of the restricted areas are used by the defence forces for exercises such as operational flying training or live weapons firing including air-to-air, air-to-ground and ground-to-air. Restricted areas extend from a lower level (often the surface) to a nominated upper level. Flight within that airspace may be restricted at all times, or may be allowed at times when the restricted area is not active.

Flight within an activated area without clearance may be extremely hazardous; even the declaration of an emergency will not guarantee safe passage although, in a declared emergency, ATS will make every effort to obtain approval to transit a restricted area, irrespective of its status. Read the article 'Military restricted areas' in Flight Safety Australia. The air navigation charts show a reference number that refers to a detail entry in the Airservices publication 'En Route Supplement - Australia' [ERSA PRD]. Details of the activation of restricted areas are promulgated by Airservices Australia in the form of NOTAM.

When activated a military restricted area usually becomes Class C airspace so is automatically denied to recreational aircraft unless the pilot and aircraft meet all the conditions specified in CAO 95.55 paragraph 7.3, CAO 95.32 paragraph 7.3, CAO 95.12 paragraph 6.3, CAO 95.12.1 paragraph 7.4 or CAO 95.10 paragraph 6.4; that is, the pilot must be authorised to operate in Class C airspace. Also the aircraft must be fitted with an operating transponder if the controlled airspace in which the aeroplane is operating requires a transponder to be fitted.

All restricted areas are allocated a 'R(estricted) A(rea) conditional status' — RA1, RA2 or RA3 which appears in ERSA to give pilots an indication of the likelihood of receiving an ATS clearance to fly through a restricted area — if there is an Air Traffic Service associated with that area and contactable via VHF radio. The status conditions are for flight planning and pilots without a submitted flight plan may request a clearance in RA1 and RA2 at any time.

Conditional status can change from day-to-day, and changed status will be notified on the activation NOTAM.

  • RA1 – pilots may flight plan through the restricted area and under normal circumstances expect a clearance from ATC

  • RA2 – pilots must not flight plan through the restricted area unless on a route specified in ERSA GEN FPR or under agreement with the Department of Defence, however a clearance from ATC is not assured. Other tracking may be offered through the restricted area on a tactical basis

  • RA3 – pilots must not flight plan through the restricted area and clearances will not be available.


Please note. CAO 95.55 section 7.1 also states:
(e) the aeroplane must not be flown inside an area designated as an area where the operation of an aeroplane, to which this Order applies, would constitute a hazard to other aircraft. CAOs 95.10, 95.12, 95.32 and the other recreational aviation part 95 CAOs contain similar rules.

Danger or alert areas usually relate to mining or quarrying sites, and to special aviation activities such as fixed training areas or aerobatic areas; it may be prudent to avoid such areas, but there is no restriction on entry. Other special use areas, for example those for hang-gliding or radio-controlled model aircraft flying, are also symbolically marked on aeronautical charts as a warning device, but there are no details available for these in any publication. Similarly, mines and quarries marked on charts, but not within a danger area, should only be overflown at a safe height to avoid blasting debris.

Designated Remote Areas are also shown on Australian charts. No VFR aircraft should attempt flight within those areas unless equipped with adequate survival gear and some form of satellite compatible radio distress beacon. The main designated remote area roughly covers all the mainland north of lines between Kalgoorlie and Bourke and between Mount Isa and Townsville. There are two other designated remote areas, the mountainous regions in the south-east corner of the mainland and in western Tasmania.

Aerial sporting activities. Aircraft, who are unaware of (or who don't take steps to avoid) gliding and hang-gliding operations or parachuting operations at drop zones, present a danger to the aerial sporting participants. The rules for gliding, parachuting and ballooning are contained in AIP ENR 5.5.

1.5 Aerodromes and aircraft landing areas

The ground sites used for powered aircraft operations range from the extremely costly international airports to the basic natural surface, private airstrip or paddock. The larger airfields are known as 'aerodromes' [ADs], the smaller are officially identified as 'aircraft landing areas' [ALAs]. The ALA term includes 'aeroplane landing areas' [also ALA] and 'helicopter landing sites' [HLS] and also seaplane water alighting areas. So, the ALA initialism can mean both 'aircraft' and 'aeroplane' landing areas.

Prior to 1992 (when the CASA authorisation under CAR 89 was removed) the ALA initialism described a CASA authorised landing area for aircraft under 5700 kg engaged in private, aerial work and charter operations. Since 1992 pilots are required to determine suitable places for their operations, but unfortunately the old, but now erroneous, 'authorised landing area' term still persists in the descriptive material of some airfields. So, do not think that CASA has determined that something described as an "authorised landing area" is a suitable place for operating your aircraft.

Civil aviation regulation 92 deals with the use of ADs and ALAs and states: A person must not land an aircraft on, or engage in conduct that causes an aircraft to take off from, a place that ... is suitable for use as an aerodrome [or ALA] for the purposes of the landing and taking-off of aircraft and, having regard to all the circumstances of the proposed landing or take-off (including the prevailing weather conditions), the aircraft can land at, or take-off from, the place in safety. See the CASA advisory circular 'Guidelines for aeroplane landing areas'.

The Civil Aviation Safety Authority recommends that aircraft with a MTOW greater than 5700 kg use ADs only. The aerodromes approved by CASA as being suitable and available for RPT operations are classified as 'certified' [CERT] or 'registered' [REG] depending on the CASA standard achieved. Only 26 of the civilian certified ADs have control towers manned by Airservices Australia personnel, the remainder (other than military [MIL] ADs) are classified as 'non-controlled'. There are about 300 CERT and REG aerodromes across Australia, ranging from the international airports to small town airfields. I have compiled a listing in text file format of CASR Part 139 Manual of Standards certified aerodromes [184] and registered aerodromes [120] but it may not reflect current status. Only 300 or so of the uncertified and unregistered [UNCR] aeroplane landing areas [ALAs] appear in ERSA but that entry does not signify that such ALAs are superior to those many ALAs lacking an ERSA entry.

Back to top

1.6 AIP Book, ERSA and NOTAM

 
Airservices Australia publishes online versions of the AIP Book, SUPS, AICs and ERSA at www.airservicesaustralia.com/publications/aip.asp (click the 'I agree' button to gain entry). To find a particular section of AIP or ERSA you have to click through a number of index pages. The section/subsection/paragraph numbering system was designed for a readily amendable looseleaf print document, so you may find it a little confusing as an online document.
AIP Book
The ICAO requires that the Aeronautical Information Service [AIS] of each member nation publish a standardised 'Aeronautical Information Publication' [AIP] that is included in a package of books, charts and other documents which together make up an 'Integrated Aeronautical Information Package' [IAIP]. The primary publication is the AIP Book, which contains longer-term operational reference information of rules and procedures written in plain language and covering civilian operations in Australian airspace.

In the AIP Book, the term 'should' implies that users are encouraged to conform with the procedure, whereas the term 'must' (or 'shall') means that the procedure is mandatory and is supported by CARs or CAOs.

Amendments are issued quarterly and supplements are issued monthly. It is not a vital document for the individual pilot certificate holder to have in print form — and it is an ongoing task to cope with the amendments — but each recreational aviation club and flight school should maintain an AIP Book print amendment subscription. AIP is essential for operations in controlled airspace.

The three standard sections of the AIP Book are 'General' [GEN], 'En route' [ENR] and 'Aerodromes' [AD]. The subsections of most interest to recreational aviation are:
  • General [AIP GEN]
    GEN 1.5 section 1 — Radio communications systems
    GEN 2.2 — Definitions and abbreviations
    GEN 2.3 — Chart symbols
    GEN 2.7 — Sunrise/sunset tables
    GEN 3.2 — Aeronautical charts
    GEN 3.3 sections 1 to 3 — Air traffic services
    GEN 3.5 all sections — Meteorological services
    GEN 3.6 — Search and rescue

  • En route [AIP ENR]
    ENR 1.1 section 17 — Operations in Class E airspace
    ENR 1.1 section 20 — Radio communication and navigation requirements
    ENR 1.1 sections 40 to 50 — Operations in Class G airspace
    ENR 1.1 sections 51 to 53 — Operational requirements — general
    ENR 1.2 — Visual flight rules
    ENR 1.4 all — ATS airspace classification
    ENR 1.7 all — Altimeter setting procedures
    ENR 5.5 all — Aerial sporting and recreational activities

  • Aerodromes [AIP AD]
    AD 1.1 — Aerodromes/heliports availability
AIP Supplements [SUP] and Aeronautical Information Circulars [AIC]
SUPs include operational information appropriate to the AIP. A SUP is published when the information is of a temporary nature and requires advanced notification such as planned military exercises that may close airspace to civil traffic. AICs contain information of a technical nature and are generally educational, giving advance notice of new facilities, services and procedures
En Route Supplement
The AIP 'En Route Supplement Australia' [ERSA] is recommended to all pilots with a cross-country endorsement — it is an essential document for cross-country flight planning and operations. ERSA contains details of PRD areas, area weather forecast codes and weather report decodes, pre-flight and in-flight information services, navigation aids, and emergency procedures.

Its main purpose is to provide, within the facilities [FAC] section, full physical details of all licensed aerodromes [ADs] with current updates relating to those aerodromes available via NOTAM. The aerodrome entry includes the VHF and HF frequencies used for air traffic services, self-announce broadcasts, flight information service, Unicom and automated weather information services. It also provides control tower operating hours and thus the times at which a Class D CTR reverts to Class G airspace.

ERSA is the only publication that indicates if a non-controlled aerodrome is certified, registered or military and thus mandates carriage and use of VHF radio when operating at the aerodrome or in its vicinity.

ERSA also lists limited detail of a number of generally privately owned 'Aeroplane Landing Areas' [ALAs]. NOTAM are usually not issued for ALAs. All ADs and ALAs listed in ERSA are identified with an unique four-letter location indicator or identity code; the first letter of which is always 'Y'. There is no information in ERSA regarding recognised water alighting areas for seaplanes.

The Aircraft Owners and Pilots Association of Australia [AOPA] publishes a biennial airfield directory containing limited information for about 2000 airfields (i.e. ADs, ALAs and airstrips), including those detailed in ERSA. More than 98% of those listed airfields are non-controlled — there are only 26 towered civilian aerodromes. Contact information for the owners/operators is included but the communications and navigation aid frequencies shown may not be current. The directory cost is about $50.
NOTAM
NOTAM, derived from the old term 'notices to airmen', are issued by Airservices Australia and contain "information or instructions concerning the establishment, condition or change in any aeronautical facility, service, procedure or hazard, the timely knowledge of which is essential to persons concerned with flight operations." The NOTAM (current at the time) are available from the Airservices Australia online pilot briefing service, which we discuss in the 'route planning' module.

The Civil Aviation Safety Authority's Visual Flight Rules Guide is recommended reading and a PDF version of the November 2011 edition is downloadable from CASA's website.

Check the Airservices Australia Publications Centre for purchase or subscription details for the publications mentioned. The charts within AIP are detailed in section 2.3.

Back to top

1.7 VMC and the visual flight rules

The two ICAO rule sets previously mentioned in section 1.1 are the Instrument Flight Rules [IFR] and the Visual Flight Rules [VFR]. Aircraft operating under the IFR are navigated by reference to cockpit instruments that process data received from ground stations or satellites. IFR flights may operate in both visual meteorological conditions [VMC] or instrument meteorological conditions [IMC] — see below. VFR flights may only operate in VMC.

All national and international RPT jet flights into or between the major Australian cities would operate only in controlled airspace (Class A while en route) and under the IFR, but turbo-prop and piston-engined regional RPT aircraft, travelling to or from a smaller city, may operate some route sectors in Class G and under the VFR. Charter and business aircraft would tend to operate in both controlled airspace under the IFR or the VFR, and in Class G under the VFR. Agricultural aircraft would normally be operating in Class G and under the VFR, and may be encountered working at low levels close to airfields. General Aviation training aircraft would tend to operate in and out of a CTR under the VFR. Military aircraft operate everywhere but particularly important to light aircraft are their low jet routes where they may be flying at very low levels using terrain-following radar.

Beware: fast-flying camouflaged military aircraft may also be encountered at very low levels outside the designated low jet routes.
Visual Meteorological Conditions in Class E and Class G airspace
RA-Aus/HGFA/ASRA operations and non-instrument rated pilot operations may only be conducted in VMC. The visual meteorological conditions (minima) applicable below 10 000 feet amsl in Class E and Class G airspace, and thus the VMC for most light aircraft operations (take-off, en route and landing) are:

  • minimum average range of visibility forward from the cockpit — 5000 metres. ('Visibility' means the ability to see and identify prominent objects. A problem is that there may not be any prominent identifiable objects when flying over featureless areas. Also, few people are adept at judging distance from the cockpit.)
  • horizontal cloud clearance — 1500 metres
  • vertical cloud clearance — 1000 feet (i.e. above and below)
  • if the visibility is less than 5000 metres or cloud clearance is below the minima, then IMC exist.

VMC minima

(The image above is courtesy of CASA's Flight Safety Australia, March–April 2002 issue)


If operating in Class G airspace at or below 3000 feet amsl or 1000 feet agl, whichever is the higher, an aircraft may operate 'clear of cloud' but remaining in sight of the ground — provided the aircraft is equipped with a serviceable VHF radio, the pilot has a radio endorsement, and the pilot listens out and transmits on the appropriate frequency. The 5000 metre visibility still applies. Note that this low-level 'clear of cloud' concession in the VMC does not apply in Class E.

Note that a non radio-equipped aeroplane can then only operate in conditions where the cloud base is 1000 feet above the flight level. Thus such an aircraft can only take off and land when the cloud base is 1000 feet higher than the circuit height, and the horizontal cloud clearance is at least 1500 metres. Even when there is no regulatory requirement, carrying VHF radio and continually maintaining a listening watch is highly recommended.

If holding a valid pilot licence enabling operations in Class D airspace (under Air Traffic Control) the VMC cloud clearance rules are relaxed to 600 metres horizontal, still 1000 feet above the cloud but 500 feet clearance below the cloud. Flight visibility remains at 5000 metres. (ATC may also permit 'special VFR' operations — within the Class D airspace — in weather conditions that do not meet the preceding criteria.)
Visual Flight Rules
The Visual Flight Rules applicable to most light aircraft operations are primarily 'see and avoid' other traffic, plus the following specifics:

  • VMC must be maintained during the entire flight (climb, cruise and descent) and the flight conducted in daylight hours
  • the pilot must be able to navigate by reference to the ground
  • position fixes must be taken at least every 30 minutes.
VFR 'on top'
In addition, an aircraft cannot be operated on top of cloud that is more extensive than scattered, unless it is fitted with serviceable flight and navigation instruments as specified in CAO 20.18 Appendix IV — which includes an artificial horizon and directional gyro. Other restrictions apply — see AIP ENR 1.1 section 18.2 'Flight under the VFR'. Taking all into account, it is probably unwise for recreational aircraft to operate above any cloud cover. See adverse weather.
Quiz question
"You are at a non-controlled airfield (elevation 2700 feet and situated in flat terrain) and the base of an extensive layer of stratocumulus has been confirmed as 4000 feet amsl but visibility exceeds 10 km. Can you legally take off and depart the airfield?"

Recreational aircraft operations (or any flight operation where the pilot in command [PIC] does not hold a night VFR rating or Command Instrument Rating) may only be conducted in VMC, and flight below 500 feet agl is forbidden except when taking off or descending to land. The visual meteorological conditions applicable below 10 000 feet amsl, and thus the VMC for take-off, en route and landing are:

  • visibility of 5000 metres
  • horizontal cloud clearance of 1500 metres
  • vertical cloud clearance of 1000 feet.
If operating in Class G at or below 3000 feet amsl or 1000 feet agl, whichever is the higher, an aircraft may operate 'clear of cloud' but in sight of the ground — provided the aircraft is equipped with a serviceable VHF radio, the pilot has a radio endorsement and the pilot listens out and transmits on the appropriate area frequency.

Thus take-off for an aircraft that is not equipped with a serviceable radio would not be legal. The minimum altitude that a non-radio flight could be undertaken is 3200 feet amsl (2700 feet elevation plus 500 feet agl), and the vertical cloud clearance is then only 800 feet. However, a radio-equipped aircraft would be legal, provided operations were conducted between 500 and 1000 feet agl, thus 'clear of cloud'. The rationale for this is that radio provides the ability to alert other aircraft — possibly operating in the same restricted flight conditions — to your presence.
VFR cruising altitudes
Recreational aeroplane flights operating in Class G under the VFR must fly at cruising altitudes, selected in accordance with the table below, when at a height above 5000 feet amsl and, whenever practicable, should be operated at the appropriate cruising altitude when below 5000 feet. The cruising altitudes for aircraft operating under the IFR are in 1000 feet steps from 2000 to 10 000 feet; thus 5000 feet amsl is an IFR cruising altitude and not available to VFR aircraft. Operating in accordance with the cruising altitudes does improve safety, but pilots should be aware that the risk of collision still exists; for example, consider an aircraft tracking 175°, while to the south another aircraft is tracking 005° at the same correct altitude. Those two aircraft could well be closing on a collision course.

As there is only 500 feet clearance between a VFR altitude and the IFR cruising altitudes above and below, it is most important that VFR pilots hold their altitude reasonably well. The aircraft flying IFR at the cruising altitudes will tend to be smaller turboprop and piston engine aircraft so not as visible as the large transport aircraft.

Sailplanes of course are not subject to these rules. Also there is nothing in the rules that prevents a situationally aware recreational pilot in an appropriately equipped aeroplane from taking off, climbing to 100-200 feet below 10 000 feet in Class G airspace, doing a couple of 360° turns to admire the landscape and descending for landing.

Magnetic tracks000° to 179°180° to 359°
Cruising
altitudes
(area QNH)
1500 feet 2500 feet
3500 feet 4500 feet
5500 feet 6500 feet
7500 feet 8500 feet
9500 feet  
VFR cruise levels


Note: there are no cruising levels available in the transition layer so VFR aircraft must not use 10 500 feet (FL105), and 11 500 feet (FL115) is not available if area QNH is below 997 hPa.
Flight at the control area lower level boundary
AIP ENR 1.4 paragraph 1.1.7 states: "When ATS airspaces adjoin vertically (one above the other), flights at the common level must comply with the requirements of, and will be given services applicable to, the less restrictive airspace." In this context Class G is the least restrictive airspace, followed by Class E, Class D, Class C and finally Class A as the most restrictive.

Thus if the lower limit of a Class C control area step was 5500 feet with Class G below, a VFR aircraft could legitimately cruise at 5500 feet in that area without requiring ATC clearance — provided of course that height keeping is good, the altimeter is very accurate and the correct QNH is set. Air traffic controllers keep aircraft at 500 feet plus above the lower level of the controlled airspace to provide clearance from Class G traffic. However, be aware that the wake turbulence from heavy aircraft sinks and drifts downwind. Also there is a problem with selecting which QNH altimeter setting to choose. So, taking everything into account, it is not a good idea to fly at the airspace intersection level.

Back to top

1.8 RA-Aus/HGFA/ASRA powered aircraft flight operations

RA-Aus/HGFA/ASRA registered aircraft must operate in VMC and in Class G or Class E, except with special permission (see below) to operate within a Class C or D control zone — such permissions are usually applied on a long-term basis and only to pilots who also hold a valid pilot licence plus the RA-Aus/HGFA/ASRA Pilot Certificate.
  • Recreational aircraft operating within Class E airspace should be radio and transponder equipped.

  • Suitably equipped recreational aircraft should also operate under the VFR. The minimum equipment list [MEL] required to do so is a serviceable magnetic compass, altimeter (accurate to 100 feet) and airspeed indicator, plus an accurate watch or clock available to the pilot.

  • All aircraft, including recreational aircraft, operating above 5000 feet amsl, must be equipped with a serviceable VHF radio; and the pilot, with an appropriate radio endorsement, must make the broadcasts specified in AIP Book.

  • RA-Aus/HGFA/ASRA aircraft may only be flown at a height of 10 000 feet above mean sea level or higher if a written approval for that flight has been issued by CASA.
Flight over cities and towns
Generally a factory-built aeroplane must not be flown over a closely-settled area at a height from which it cannot glide clear of the closely-settled area to a suitable landing area and the minimum height is 1 000 feet above ground level. 'Suitable landing area' means an area in which an aeroplane can be landed without endangering the safety, or damaging the property, of persons unconnected with the aeroplane.

Home-built — and some factory-built — aeroplanes are prohibited from flight over closely-settled areas, but for expanded information see 'Flight over the built-up area of a city or town'.
Recreational aircraft operations in Class C and D control zones
To operate in Class C and D control zones, the recreational aircraft and the engine must either be certificated to the design standards specified in CAO 101.55 para 6.1 or meet criteria specified in the exemption CAOs (e.g. see paragraph 7.3 (a) ii and iii) in CAO 95.55); be fitted with a certificated or CASA-approved engine and is fitted with a radio capable of two-way communication with air traffic control; and the pilot in command must hold a valid Pilot Licence ( i.e. Private Pilot Licence — PPL, Commercial Pilot Licence — CPL, Air Transport Pilot Licence — ATPL) in addition to the Pilot Certificate. Even so, it is unlikely that, if it came to a judicial test, a recreational aircraft would be legally be able to operate from, or enter, most Class D CTRs as the 'lanes of entry' to such airfields usually involve overflight of closely-settled areas, and overlying Class C airspace may severely limit available altitude (and thus gliding distance) in such lanes.

A transponder must be operated in Class C CTRs and CTAs.

Recreational aircraft must comply with the flight conditions specified in the relevant exemption CAO. For example section 7.1 (h) of CAO 95.55 forbids flight of factory-built aircraft over a closely-settled area at a height from which it cannot glide clear of the closely-settled area to a suitable landing area; and that is lower than 1000 feet above ground level. Home-built aircraft must not be flown over a closely-settled area except under conditions and limitations that CASA or an authorised person considers necessary.

Be mindful that it is the legal responsibility of the pilot, not the ATS personnel, to ensure compliance with the exemption CAOs and other regulations. Air traffic controllers presume that the pilot of an aircraft requesting entry into their airspace is legally, medically and practically qualified to do so and a subsequent airways clearance does not absolve the pilot of legal responsibility. Also bear in mind that the entities owning Class C and D aerodromes (and others) may publish their own 'conditions of use' which users should be aware of, and comply with.

Recreational aircraft, operating under the Visual Flight Rules with area QNH set, may cruise at any safe altitude below 5000 feet above mean sea level. However, a prudent pilot undertaking a flight of reasonable length would choose a hemispherical VFR cruising altitude whenever practicable. For any aircraft track with an easterly component, the VFR cruising altitudes are 1500 and 3500 feet below 5000 feet; plus 5500, 7500 or 9500 feet if the aircraft is radio-equipped.



Back to top

1.9 Communication and navigation aids

Civil aviation radio communications are conducted primarily in the aviation very high frequency [VHF] communications [COM or COMMS] band, 118.00 to 136.975 MHz, where, at 0.025 MHz steps, there are 760 channels possible. In the less accessible areas of Australia, where there is no VHF ground coverage, communications must be in the various high frequency [HF] network bands between 3400 and 9500 kHz. The PCA shows VHF coverage (but not FIA boundaries or frequencies) and the appropriate short-wave frequencies in the three domestic HF network areas. Military aircraft primarily use UHF communications.

There is an inter-pilot air-to-air communications frequency available at 123.45 MHz. More information on frequency allocation for club, sport aviation and other aviation activities is contained in the aircraft station operating frequencies section of the VHF Radiocommunications Guide.

In Australia, the VHF Omni-directional Radio Range [VOR] primary air route, homing and position-fixing navigation aids operate in the 112.1 to 117.975 MHz aviation VHF navigation [NAV] band. The Instrument Landing System runway localisers at larger airports operate in the 108.00 to 112.00 MHz VHF NAV band. Thus the aviation VHF NAV/COM band is from 108.00 to 136.975 MHz, with some 200 channels (at 0.05 MHz intervals) in the NAV band and 760 in the COM band. Some hand-held airband COM transceivers have a very limited VOR receiver capability, but the full NAV/COM capability is confined to more expensive panel-mounted transceivers/VOR receivers/VOR indicators coupled to a VOR antenna.

Non-directional aviation radio beacons [NDBs], installed to provide a homing facility for smaller aircraft, transmit in medium wave bands between 190 and 535 kHz. The companion airborne automatic direction finding receivers [ADFs] can also pick up transmissions in the 520 to 1611 kHz AM broadcast band, depending on the power output of the radio station. The broadcasting frequency, latitude and longitude, power output in kW and the height of the mast agl (quite a few are over 600 feet agl and situated on the high ground) for all AM broadcast stations, is contained in the ERSA NAV/COMMS section. The location of some AM broadcast stations' transmitter masts is shown on World Aeronautical Charts [WACs], with the station identification but not the frequency. Most licensed aerodromes have an NDB and many would have a VOR.

Back to top

1.10 Distress frequencies and AusSAR

When a pilot is experiencing in-flight difficulties, it is advisable to inform others as early as practical and to advise whether the pilot considers the situation to be an emergency or something less. The frequency on which a distress call (a MAYDAY transmission) or an urgency message (a PAN-PAN transmission) is made should be that which is likely to provide a quick response — usually the area frequency.

If a registered civil or ultralight aircraft comes to grief away from a controlled aerodrome or is reported missing, Australian Search and Rescue [AusSAR] has national responsibility for coordinating the search and rescue. More information is contained in the safety and Safety and emergency communication procedures module of the 'Coping with Emergencies Guide'.

Top of page




Groundschool — Flight Planning & Navigation Guide

| Guide content | [1. Australian airspace regulations] | 2. Charts & compass | 3. Route planning |

| 4. Effect of wind | 5. Flight plan completion | 6. Safety audit | 7. Airmanship & flight discipline |

| 8. En route adjustments | 9. Supplementary navigation techniques | 10. Global Positioning System |

| 11. Using the ADF | 12. Electronic planning & navigation | 13. ADS-B surveillance technology |


Supplementary documents

| Operations at non-controlled airfields | Safety during take-off & landing |



Next - charts and compass Section 2 of the Flight Planning & Navigation Guide discusses Australian navigation charts and the aircraft compass





Copyright © 2001–2014 John Brandon     [contact information]