Australian CASA Rules: The 3 Nautical Miles Question

A question arose at Swarm UAV recently regarding paragraph 101.075 of the CASR 1998.The regulation seems straight forward at first glance but quickly becomes trickier when trying to fly a UAV close to the 3 Nautical Mile boundary from an airport. At this point the following question arises “Where is 3 Nautical Miles measured from?”

Three potential answers to this were put forward before the issue was decided: the aerodrome reference point, the nearest threshold, and nearest aerodrome boundary. Each of these options has pros and cons in terms of both air safety and operational restrictions.

The aerodrome reference point is defined as “The designated geographical location of an aerodrome” (AIP Gen 2.2). This is used by pilots of manned operations as the physical location of the aerodrome for use in navigation. They can be found in the En-Route Supplement Australia (ERSA) on each aerodromes page along with a latitude and longitude of that location. The biggest pro of measuring 3 nautical miles from the aerodrome reference point is ease of use. This is the location that is used whenever an Electronic Flight Bag app such as OzRunways tells you the distance from an aerodrome. This makes checking compliance while in the field a breeze. Other points in favor are that this means that UAV operations are in line with manned operations instead of there being two separate sets of rules and it is the least restrictive of all the options, allowing UAVs access to a greater number of sites. The largest con for using the aerodrome reference point to measure three nautical miles will be that it potentially brings manned operations on an approach to land or in the process of departing an aerodrome closer which could create a safety issue. Obviously no commercial operator or anyone in the larger UAV community wants to be responsible for an accident of this type or to see it happen at all but the question of how much using the aerodrome reference point would reduce safety is an interesting one.

The nearest threshold is an answer I received from a number of people in CASA while researching this question. To an extent, using the nearest threshold to measure three Nautical Miles makes sense. This is the area to which aircraft travel for landing so this provides the clearance at one of the most vital and vulnerable stages of flight. It can also be measured quite easily using Google Maps and isn’t difficult to pinpoint. However problems arise when trying to check this on the run. Although Google Maps can measure distance as the crow flies, the mobile app can’t, and OzRunways is using the aerodrome reference point – these are the two easiest ways of checking distance in the field. The good old fashioned fall back of a paper map uses the aerodrome reference point as well. In the mean time you have a client on site asking for a specific shot that takes you closer to an aerodrome, you know that the site you’re shooting is just outside 3 Nautical Miles but how much closer can you get? Measuring from the threshold just doesn’t stand up to being used in the field.


Lastly we have the actual answer – 3 nautical miles from the aerodrome boundary. Using the aerodrome boundary has the same issues as using the threshold and creates an even larger area in which operating either isn’t allowed or requires a lengthy process to obtain an Area Approval. It is also harder to pinpoint the aerodrome boundary using Google Maps. The benefit of this option is increasing the separation between manned and unmanned aircraft but how much separation is really needed between a UAV and a parked aircraft? What about a taxiing aircraft? In both of these cases 3 nautical miles seems excessive. Luckily Airservices Australia have released maps of the no fly zones around many of the major controlled aerodromes however there are still some yet to be created. These are also unlikely to be created for all other aerodromes which need to be avoided as well. Although this option may look the best in terms of providing separation between UAVs and manned aircraft it makes it harder for UAV operators to follow the rules consistently. This increases the risk of an operator flying in an area they’re not supposed to, which would decrease safety in an unpredictable manner.

There are two key issues that need to be addressed further for the current system to work – usability and education. If the aerodrome limits are to be measured from the aerodrome boundary then a better system needs to be in place for people to determine where this is while on site. This also needs to be in place for all registered aerodromes not just ones at which an air traffic control service is in place. If this isn’t done then even though conscientious UAV operators may check some will simply not know about an aerodrome in their area – the ERSA has 687 entries. Which brings me to the second point, education. CASA are an organisation that does great work educating the aviation community on both the regulations that govern aviation operations and safety issues. The work I’ve personally seen them do promoting a safety culture is exceptional and their magazine Flight Safety Australia is fantastic. On this particular issue however I feel more should be done. The only mention of using the aerodrome boundary as a point of reference is found on the Airservices Australia website. This information should be readily available and visible on the CASA website and included if not in legislation at least in an Advisory Circular.

Safety is always going to be one of the biggest considerations in any part of the aviation industry, however, any safety system or set of regulations must be usable by the person or group operating under the system. In this case although the general idea of separation is a sensible and even necessary one the implementation leaves something to be desired.   

If you are interested in learning more about CASA’s operators certificate and what is required have a read through one of our previous blogs about obtaining your CASA operators certificate.

Swarm UAV

We are Australian specialists in drone aerial photography and aerial cinematography. CASA Certified Pilots. We are a business with our heads in the clouds, and our feet firmly on the ground.

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