Free Route Airspace: A New Era in Flight Planning

The concept of free route airspace is not new. While the terminology may differ – free route airspace, user preferred route, random route – it has been used in oceanic airspace for years before the transition to continental airspace. While the United States had implemented their version of random routing (High Altitude Routing (HAR)) and Canada had permitted random routing for eligible polar flights in the early-2000s, Europe can be credited with bringing the concept of free route airspace to a global scale. Portugal was the first country within the EU to implement Free Route Airspace (FRA) in 2009, and EU 2021/116 has required all EU-member states to adopt FRA by the end of 2025.

Benefits and Strategic Goals of FRA

For a start-up, laying a strong operational foundation is essential to compete in the market and achieve sustainable growth. PPS Flight Planning supports this by automating processes and providing tools that optimize efficiency across the whole flight operations.

Automated Flight Planning and Dispatch

The design of free route airspace entails the eventual removal of the ATS network and installation of unpublished DCTs between a fixed set of waypoints. These waypoints designated as FIR or FRA boundary waypoints are considered as entry or exit points which funnel traffic by fixed waypoints in or out of an airspace. Waypoints within the FRA can be designated as intermediate points allowing connections between various points within the FRA but also to departure or arrival waypoints used to SID/STAR purposes. Despite the various designators, the intent of the airspace design is to allow enough waypoints to connect to in order to allow increased optimization while not allowing every potential waypoint to limit the exponential number of connections. By doing so, it was expected to increase route efficiency while decreasing congestion and delays.

Challenges and Operational Complexities

With the introduction of FRA, it became evident that the ‘free’ airspace reduced predictability and permitted flights to areas within the airspace that were previously not flown. This resulted in a number of new preventative measures being created by various ANSPs to mitigate this. No Planning Zones were introduced to prevent flights from being planned in airspace that was historically off-limits in an ATS environment. In the early days of FRA, it was found that DCTs were being created between two waypoints in a single FIR, but would overfly an adjacent FIR’s airspace. Thus, regulations were created to prevent the use of border clipping, thereby requiring a flight to stay X-number of nautical miles away from the FIR boundary. This distance varies between ANSP; however, the intent remains the same – keep the flight in a single FIR to prevent unnecessary handovers between Controllers.

Of course, the RAD is the most obvious complexity with an increase in RAD, new RAD concepts, and utilization to create traffic flow. It can be argued that the RAD is used extensively in some states to mimic the former ATS network through the utilization of dependent-applicability RAD requirements. More recently, GATE RADs have been created to force traffic between specific waypoints as a means to/from aerodromes.

Finally, there are differences within Europe between the block of FRA airspace and the activation times of the FRA. The result is that a flight at a specified cruising altitude may switch between FRA and ATS airspace depending on how low the FRA floor is of a particular FIR. The same applies to FRA applicability time. Newer state implementations often begin with FRA overnight and during weekends. Outside of these hours, FRA is not permitted. This results in inconsistent flight plan routes deviating between FRA and ATS segments.

Implications for CFSP Systems

The impact to CFSPs differs between each company.  In order to remain compliant and to provide airlines with the optimal route, CFSPs have had to remain abreast of the nuances enacted by different ANSP implementation schemes.  This results in FRA-specific databases being created to specify the permitted actions to be taken in that particular FRA airspace.  These actions include considerations of:

• DCT leg distance or time
• Waypoint type selection
• FRA FL block and activation times

The result is increased computational requirement on the CFSP system to account for the unique requirements as well as the exponentially large number of DCT combinations that could be created amongst waypoints.  From an end-user standpoint, this would appear to be the system taking longer to provide a route as the system has to consider all potential connections.  To alleviate the impact to airlines, CFSPs have introduced their own methodology.  These introductions include:

• Creating fixed DCTs
• Limiting the number of waypoints to consider
• Narrowing the airspace to search for routes

Ultimately, these mitigations go against the intention of FRA and the CFSP must strike a balance between providing optimal routes while enabling the dispatcher to properly build and manage the flight.

Source: EUROCONTROL

The Future of Free Route Airspace

While EU 2021/116 mandates all EU member states to implement FRA by December 31, 2025, many states have moved beyond that and are now introducing cross-border FRA. This allows for much longer DCT segments without using a FIR boundary point. Operationally, this would appear to be quite efficient; however, from a flight planning optimization standpoint, the opposite is true. Short DCT segments allow for greater optimization to account for weather, winds, airspace constraints, etc.

Globally, the concept is being adopted. Post-COVID, Australia allowed free route airspace through their Off-Airway Route Plan. The United Arab Emirates introduced FRA in 2024. Mongolia has held a FRA workshop exploring the implementation.

As the industry seeks to remove complexity, embrace new routing options, and have a focus on optimized routes, it is anticipated that more states will move to implement FRA. Europe has provided an example to the world for others to follow.

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