Airspace and separation

Safe separation between aircraft is fundamental to Part 135 non-scheduled passenger operations.

Regular public transport services generally operate within controlled airspace and established airline routes. Part 135 operators regularly:

transition between controlled and non-controlled airspace
operate into regional and remote aerodromes
share airspace with a wide range of aircraft conducting different types of operations.

These operations often involve:

interaction with flight training aircraft
helicopters
agricultural aircraft
recreational aircraft
gliders
remotely piloted aircraft systems (RPAS).

Factors that can increase complexity, particularly around non-controlled aerodromes and during periods of high traffic activity, include differences in:

aircraft performance
pilot experience
operating procedures
communication practices.

Safety data supports the importance of this issue. Aircraft separation events, including communication-related occurrences, remain one of the most significant safety themes within the Part 135 occurrence profile.

Many of these events do not result in an accident. However, the ATSB has assessed a notable proportion as higher-risk occurrences using their Event Risk Classification (ERC) methodology. Safety factor analysis also notes aircraft separation and communication issues as recurring contributors across the sector.

They discussed several challenges, including:

mixed traffic operating at non-controlled aerodromes
busy Common Traffic Advisory Frequencies (CTAFs)
increased collision risk in high traffic environments
airspace design, including interactions between Required Navigation Performance (RNP) approaches and Visual Flight Rules (VFR) traffic
helicopter operations operating alongside fixed-wing aircraft
increasing RPAS activity.

During the bowtie validation exercise, they also found several additional threats that influence the risk of mid-air collision. These included:

RPAS operations
RNP approach design
paragliders operating without radios or transponders
poor visual lookout.

Discussions also included runway incursions associated with runway crossings at non-controlled aerodromes and the use of non-standard air traffic control phraseology.

Maintaining effective separation relies on a combination of:

procedures
communication
situational awareness
sound judgement.

Although air traffic services provide separation in many controlled environments, pilots remain responsible for:

maintaining situational awareness
complying with operating procedures appropriate to the airspace in which they are operating.

Operations at non-controlled aerodromes require pilots to build an accurate mental picture of surrounding traffic using:

radio broadcasts
visual scanning
knowledge of local procedures.

Aircraft separation events continue to present a recurring challenge. Rather than deficiencies in aircraft performance, many reported events involve:

communication
procedural compliance
situational awareness.

Differences in aircraft performance and operating profiles may increase the complexity of these environments. For example, slower training aircraft, helicopters conducting circuit operations and faster turbine aircraft may all be operating simultaneously within the same aerodrome environment.

The increasing use of RNP approaches has improved access to regional aerodromes and enhanced capability. However, instrument approach paths may intersect areas commonly used by VFR traffic.

Additionally, the continued growth in RPAS operations means their increasing presence near aerodromes and low-level operating areas requires operators to consider how they may affect:

flight planning
situational awareness.

What you can do

Operators can reduce airspace and separation risk by incorporating appropriate controls into their procedures and Safety Management System. Practical strategies include:

ensuring flight crews understand the airspace structure and procedures for each destination
conducting comprehensive pre-flight briefings that note known traffic hotspots, training areas and local operating practices
reinforcing standard radio phraseology and timely position broadcasts at non-controlled aerodromes
promoting effective visual scanning techniques and reinforcing that radio broadcasts do not replace the requirement to maintain a lookout
establishing standard operating procedures for operations into busy or unfamiliar aerodromes
incorporating threat and error management principles into flight planning and briefings
ensuring flight crews understand the interaction between IFR procedures and VFR traffic at mixed-use aerodromes
providing recurrent training that includes communication, situational awareness and collision avoidance scenarios
encouraging pilots to report airspace hazards, communication issues and separation events through the Safety Management System
reviewing reported occurrences to find trends and implement corrective actions
engaging with aerodrome operators, Airservices Australia and other operators where you have noted recurring airspace issues
maintaining awareness of emerging technologies, including RPAS operations and electronic conspicuity systems.

What we have done

We continue to support the safe integration of aircraft operating in Australian airspace through education, surveillance and collaboration with industry and other aviation agencies.

Current activities include:

publishing guidance material relating to operations in controlled and non-controlled airspace.
providing educational resources that support communication, situational awareness and collision avoidance:
- Be heard, be seen, be safe (PDF, 1015.04 KB)
promoting standard operating procedures and standard phraseology through safety education initiatives.
supporting the adoption of electronic conspicuity technologies where appropriate - Automatic Dependent Surveillance (ADS-B) Broadcast Rebate Program. It encourages VFR aircraft owners to install ADS-B equipment. This will improve safety and efficiency for Australian airspace users. The program runs through until mid-2027
working with Airservices Australia and industry to find emerging airspace safety issues - a webinar with an Air Traffic Controller on controlled aerodromes
monitoring occurrence trends associated with aircraft separation, communication and compliance
incorporating industry feedback into ongoing safety intelligence, surveillance planning and regulatory risk analysis.

More information about radio procedures and non-controlled aerodromes is available from:

We also continue to support safe integration of RPAS through education, surveillance and regulatory oversight. This is because we recognise the increasing interaction between remotely piloted and crewed aircraft across Australia's aviation system.

Published date: 21 September 2026