What is Air Blown Fibre?

Fibre optic networks form the backbone of modern telecommunications, but how that fibre gets from point A to point B matters just as much as the fibre itself. Traditional methods involve pulling cables through conduits—a process that works but comes with limitations when networks need to grow and change.

Air blown fibre technology offers a fundamentally different approach. Instead of pulling cables under tension, this method uses compressed air to propel lightweight fibre cables through small plastic tubes called microducts. The result is a more flexible, scalable, and future-ready network infrastructure that’s transforming how operators plan and deploy fibre networks worldwide.

In this guide, you’ll learn exactly how air blown fiber systems work, where they make the most sense, and how they compare to conventional cabling methods. Whether you’re planning an FTTH rollout, upgrading a campus network, or designing infrastructure for a data center, understanding this technology will help you make better decisions about your network design.

What is air blown fibre?

Air blown fibre is an installation method where micro optical fiber cables are propelled through pre installed microducts using compressed air rather than mechanical pulling. The fibre cable essentially floats on a cushion of air as it travels through the duct, with the airflow creating a drag force that moves the cable forward while a machine at the entry point provides gentle mechanical pushing.

This approach differs fundamentally from traditional cabling where cables are attached to a pull rope and winched through conduits under significant tensile stress. With air blown installation, the cable makes minimal contact with the duct wall because the compressed air acts as a lubricant, lifting the cable away from the surface. This dramatically reduces friction and eliminates the mechanical stress that can damage optical fibre during installation.

A typical installation involves microduct bundles—often containing 7 to 24 individual color-coded tubes—installed within larger ducting pipe under streets, along building risers, or through cable trays. These microducts are manufactured from flexible materials like HDPE with smooth, low-friction inner surfaces. Once the duct infrastructure is in place, fibre cables can be blown in whenever capacity is needed, rather than installing all the fibre upfront.

Modern blowing equipment can achieve speeds of 100 to 150 metres per minute in access networks, with some systems reaching up to 500 feet per minute under optimal conditions. Single blowing runs can cover several hundred metres to several kilometres depending on duct diameter, cable type, route complexity, and the number of bends in the path.

Air blown fiber technology is primarily used where networks need to be easy to expand and reconfigure over time. This includes FTTH access networks serving residential and business customers, enterprise campuses with evolving connectivity needs, data centers requiring high-density fibre between racks and buildings, and 5G fronthaul connecting distributed antenna systems. The technology excels in environments where network requirements will change over the 20 to 30 year lifespan of the physical duct infrastructure.

How does air blown fibre work?

The air blown fiber approach separates infrastructure installation into two distinct phases: first the microducts are installed during civil works, then the fibre cables are blown in later as capacity is required. This separation is what gives the technology its flexibility and scalability advantages.

The system comprises several key components working together. Micro ducts are small HDPE tubes typically ranging from 5 to 16 millimetres in diameter, featuring smooth inner surfaces that minimise friction. These are often bundled together—up to 24 color-coded microducts in a single sheath—creating a multi-cell assembly that can be installed in existing larger conduits or directly buried. The fibre cables themselves are specially designed microcables with optimised outer diameters, smooth sheaths, and appropriate stiffness for blowing. These range from single-fibre units for drop connections to optical fiber bundles containing 12 to 864 fibres for feeder applications.

The blowing apparatus consists of a jetting machine that grips the cable with drive wheels or belts and pushes it into the microduct while an air compressor injects compressed air at typically 8 to 15 bar. The injected air flows through the duct at much higher velocity than the cable moves, creating a drag force along the cable’s length that propels it forward. Rubber seals around the cable entry point create an airtight chamber, ensuring the air pressure pushes effectively. The far end of the microduct remains open to prevent pressure buildup and allow continuous airflow.

What makes this work mechanically is that the cable is supported by air and boundary layer effects, so it has minimal contact with the duct wall. This reduces friction dramatically compared to pulling methods. Modern blowing equipment can log distance, speed, and air pressure throughout the process, making it straightforward to plan installations in complex routes with multiple bends and to replicate successful parameters across similar runs.

The contrast with traditional pulling is significant: no winch rope is required, lubricants are rarely needed, and there’s far less risk of microbending and fibre damage. The cable experiences near-zero tensile stress during installation, arriving at its destination in the same condition it left the manufacturer—something that cannot always be said for pulled cables.

History and development of air blown fibre

Air blown fibre emerged in the 1980s as network operators sought better ways to upgrade and expand their duct-based infrastructure. The limitations of traditional cable pulling—particularly the difficulty of adding new fibres to fully occupied ducts and the mechanical stress on cables—drove research into alternative approaches.

British Telecom began developing blown fibre concepts in the early 1980s, recognising that separating duct installation from fibre deployment could dramatically simplify upgrades in dense urban networks. Their pioneering work established the fundamental principle that compressed air could propel lightweight fibre cables through small tubes, eliminating the need for pulling under tension.

True cable jetting technology—combining mechanical pushing wheels with compressed air propulsion—was pioneered in the late 1980s by Willem Griffioen at KPN Research in the Netherlands. This innovation addressed the practical limitations of air propulsion alone, particularly for longer distances and routes with multiple bends where air pressure alone couldn’t overcome accumulated friction.

During the 1990s, equipment manufacturers industrialised the technology. Companies like Plumettaz in Switzerland developed commercial jetting machines capable of reliably blowing cables hundreds of metres to several kilometres in a single run. This period also saw the rise of bundle blowing—installing multi-cell microduct bundles inside existing larger ducts to create many future fibre paths without additional civil works.

From the 2000s onward, blown fibre became strongly associated with large-scale network deployments. FTTH rollouts across Europe embraced the technology for its ability to connect customers on demand rather than overbuilding infrastructure. Metro access rings, enterprise campuses, and increasingly 4G and 5G mobile backhaul networks adopted blown fibre for its flexibility. The technology that british telecom pioneered had evolved into a preferred architecture for delivering telecommunications service in access and distribution networks worldwide.

Advantages of air blown fibre

The advantages of air blown fibre systems span mechanical, operational, and economic dimensions compared to traditional fiber systems. Understanding these benefits helps network planners evaluate where the technology makes strategic sense.

Mechanical benefits represent perhaps the most fundamental advantage. Installing blown fibers ensures the cable experiences zero tensile stress during deployment—the fibre is pushed and floated rather than pulled under tension. This eliminates the microbending and potential damage that can occur when cables are winched through ducts, resulting in more stable attenuation over the cable’s lifetime and increasing system performance from day one. Glass fibre optic cables are inherently fragile when subjected to tensile loads, making this gentler installation method particularly valuable for maintaining optical integrity.

Scalability transforms how operators approach capital expenditure. Rather than installing all anticipated fibre capacity upfront, operators can install ducts once during road or building works, then blow in fibres incrementally as actual demand materialises. This pay-as-you-grow model avoids overbuilding dark fibre and spreads investment over time. When more fibres are needed, crews simply return with blowing equipment to populate empty microducts—no trenches, no disruption.

Upgrade flexibility extends the value of the physical infrastructure over decades. Existing microcables can be blown out and replaced with higher fibre-count cables or newer fibre specifications when technology advances. An operator who installed G.652.D singlemode fibre can later upgrade to bend-insensitive G.657.A2 fibre without touching the civil infrastructure. This future proofing capability means the microduct network installed today can support future evolving applications for 20 to 30 years.

Installation efficiency delivers immediate project benefits. Higher blowing speeds—reaching several hundred metres per minute—accelerate deployment timelines. The ability to navigate complex routes with multiple bends in a single run reduces the need for intermediate access points. Achievable distances between splice points extend to several kilometres under suitable duct conditions, simplifying network topology.

Network design benefits flow from reduced splice requirements. Fewer fiber connection points mean simpler branching at access locations, reduced optical loss, and lower failure points across the network. Point-to-point installations from cabinet to customer premises can eliminate splices entirely, lowering attenuation and simplifying troubleshooting. The result is a cleaner network with fewer closures and joints to maintain.

Cost savings accumulate across the network lifecycle. Reduced need for repeat civil works represents the largest savings—digging up streets is expensive, disruptive, and increasingly difficult to permit. Less labour per additional customer connection improves the economics of connecting new subscribers. Lower long-term maintenance costs from simplified repairs and fewer splice points contribute to total cost of ownership advantages that compound over the infrastructure’s lifespan. For many access networks, air blown fiber represents a cost effective solution when evaluated over a 15 to 20 year horizon.

Where is air blown fibre used?

Blown fibre technology is most attractive in branched, changeable networks where customer connections are added incrementally and future requirements are uncertain. Simple, long, straight links with stable capacity needs typically don’t benefit as much from the technology’s flexibility.

FTTH and FTTB access networks represent the most common application for blow fiber ftth deployments. Microducts run from street cabinets or distribution points to multi-dwelling units, business parks, and residential premises. When a customer orders service, technicians blow the fibre from the cabinet to the end user’s premises—no pre-installed dark fibre sits unused, and no splicing is required at intermediate points. This on-demand connection model transforms the economics of serving areas with uncertain take rates.

Data centers and enterprise campuses leverage blown fibre for high-density connectivity between racks, buildings, and data halls. These environments experience frequent moves, adds, and changes as equipment is deployed, upgraded, and reorganised. Spare microducts provide pathways for new connections without running new cable trays or disrupting existing infrastructure. The ability to blow out old cables and install new fibers with higher counts or different specifications supports the continuous evolution of these facilities.

Mobile and 5G networks increasingly rely on blown fibre for fronthaul and backhaul connections. Small cells on streetlights, rooftop sites, and distributed antenna systems require fibre connections that may need to be added gradually as coverage expands. Micro tubes installed during initial deployment can accept additional fibres as the network densifies, supporting the phased rollout typical of mobile infrastructure investments.

Utility, transport, and smart city networks benefit from the technology’s longevity and reusability. CCTV systems, traffic management, IoT sensors, railway corridors, and road tunnels all require fibre infrastructure that may serve evolving purposes over decades. Ducts installed for one application can later support entirely different services—the same flame retardant micro tubes in a building riser might initially serve security cameras and later support building automation or tenant connectivity.

Indoor versus outdoor applications are both equally suitable for blown fibre. Indoor applications use flame-retardant microducts and cables rated for risers and plenum spaces, while outdoor installations employ ruggedised ducts suitable for direct burial or installation as sub-ducts within existing infrastructure. This versatility means a single technology approach can span from the street to the telecommunications room.

Air blown fibre vs traditional fibre cabling

Both air blown and traditional pulled fibre methods remain relevant, chosen based on network architecture, fibre counts, and expansion plans. Understanding where each excels helps planners select the right approach for each network segment.

Traditional cable pulling excels in specific scenarios. Long, high-fibre-count trunk routes carrying 144, 288, or more fibres are typically best served by conventional cabling methods. These routes are planned years in advance, unlikely to change, and benefit from the simplicity of a single large cable. Submarine links, intercity backbone routes, and simple point-to-point runs with few or no branches similarly favour traditional approaches where the pulling stress is manageable and the network topology is stable.

Blown fibre’s strengths emerge in access networks with many branches, frequent customer additions, and uncertain growth patterns. Where ducts can be pre-installed during road construction or building fit-out—with fibre added later as demand materialises—the technology delivers maximum value. Networks serving areas with limited access for future construction particularly benefit, as do environments expecting many network changes over time.

Practical installation differences are significant. Traditional pulling uses winches, pulling ropes, and lubricants to drag cables through conduits. This requires access points at both ends simultaneously and careful tension monitoring to avoid cable damage. Blowing uses jetting machines and compressed air with smaller installation teams, often requiring access only at the entry point. Routes with multiple bends that would challenge pulling operations can often be navigated in a single blowing run.

Cost trade-offs favour different approaches depending on network evolution. Traditional cabling has lower upfront material costs when all required fibre is installed at once. However, blown fibre systems—despite requiring investment in microducts and blowing equipment—pay off when networks evolve over 10 to 20 years with many incremental changes. Each time a new connection is added without trenching, the microduct investment returns value. For stable networks with predictable capacity, traditional methods remain economical.

Technical performance is comparable between the approaches—the same fibre types and bandwidth capabilities apply to both. However, blown designs often achieve lower splice counts and more consistent optical budgets in branched access networks because point-to-point installations eliminate intermediate joints. High fiber count connections in trunk applications may still favour traditional high-count cables.

Mixed architectures are common and often optimal. Traditional high-count trunk cables feed central offices and major distribution points, while blown-fibre-based distribution and drop segments connect individual customers and buildings. This hybrid approach leverages the strengths of each technology where they apply best, using air blown technologies for the flexible access layer while maintaining traditional approaches for stable backbone infrastructure.

Planning and installing an air blown fibre system

A successful blown fibre network depends on careful duct design, appropriate cable selection, and controlled installation practices. Poor planning at any stage can limit blowing distances, require additional splice points, or reduce the network’s future expansion capability.

Microduct network planning begins with route design from central offices or fibre distribution hubs through to cabinets and ultimately to customer premises. Key decisions include choosing duct diameters appropriate for the cable sizes anticipated (both current and future), determining the number of cells needed in bundle assemblies, and establishing colour coding schemes for easy identification. Predefined routes should account for all known potential connection points while leaving spare capacity for unanticipated growth.

Duct quality considerations directly impact achievable blowing distances and installation success. Low-friction inner surfaces are essential—the smoother the duct interior, the further fibres can be blown. Suitable bend radii must be maintained throughout the route; sharp bends dramatically increase friction and limit run lengths. Installing flexible microducts requires attention to avoiding kinks, crushes, or damage that could create bottlenecks. Where ducts pass through harsh environments, appropriate protection ensures long-term integrity.

Microcable selection should match the application and duct infrastructure. Optimal outer diameter relative to duct inner diameter balances blowing performance against future upgrade options. Smooth cable sheaths reduce friction, while appropriate stiffness ensures the cable can be pushed without buckling. Weight and friction characteristics of the cable affect maximum blowing distances. Singlemode fibre types should suit the application—standard G.652.D for most deployments, bend-insensitive G.657.A2 for tight-radius installations in buildings and drop cables.

Installation steps follow a consistent sequence. First, pressure test and clean the ducts to verify integrity and remove any debris. Then set up the blowing equipment at the entry point, ensuring proper sealing around the cable entry. Feed the cable through the machine’s drive mechanism, verify grip pressure, and begin the blowing process while monitoring speed, distance, and air pressure. Continue until the cable exits at the far end or reaches the target termination point. Complete the installation by terminating the cable at closures, distribution cabinets, or patch panels as the network design requires.

Quality and safety practices round out professional installations. Adherence to local regulations for working with compressed air and in confined spaces protects personnel. Plant material and documentation of duct occupancy—which microducts contain cables, which remain spare—enables future upgrades and simplifies repairs. Recording installation parameters for each run builds knowledge that improves future planning. This documentation proves essential when returning months or years later for fiber expansion or redundant network installations.

Future outlook for air blown fibre

Demand for flexible, high-density fibre infrastructure continues growing as cloud services, 5G deployment, IoT proliferation, and smart city initiatives expand connectivity requirements. Network operators face increasing pressure to deploy fibre quickly while maintaining flexibility for future growth—conditions that favour air blown approaches.

Technology evolution continues across all system components. Higher fibre-count microcables enable more capacity through existing microducts. Improved low-friction duct materials extend achievable blowing distances. More automated blowing machines with digital monitoring simplify installations and improve quality control. These incremental improvements steadily enhance the technology’s capabilities and cost-effectiveness.

Duct-first strategies are becoming standard practice in many jurisdictions. Cities, utilities, and transport authorities increasingly mandate or incentivise installing microduct infrastructure during any road or building works, creating pathways for future fibre without knowing exactly when or what fibres will be needed. This approach minimises disruption from repeated excavations over a 20 to 30 year infrastructure lifecycle and positions networks for rapid service activation when demand emerges.

Converged networks represent a growing trend where the same duct infrastructure serves multiple applications. A single microduct bundle might carry fibres for residential broadband, mobile backhaul, municipal CCTV, traffic management systems, and private enterprise connections. This not so obvious application of shared infrastructure maximises the value of civil works investments while enabling each service to evolve independently. Simply blowing new fibres into spare ducts when new applications emerge avoids the coordination challenges of shared cables.

Looking ahead, air blown fibre is positioned to remain a preferred system for scalable access and campus networks worldwide. The fundamental advantages—mechanical gentleness, installation efficiency, and future upgrades without civil works—address persistent challenges in network deployment. While traditional high-count cables will continue serving backbone and trunk applications, the access layer increasingly favours the flexibility that blown fibre provides. For network planners focused on delivering telecommunications service efficiently today while preserving options for tomorrow, understanding and deploying air blown fiber technology represents an ideal solution that balances immediate needs against long-term network evolution.

The technology pioneered decades ago by researchers seeking better ways to deploy fibre has matured into a robust, well-understood approach used worldwide. As bandwidth demands grow and networks become more complex, the ability to add capacity incrementally—without disrupting streets, buildings, or existing services—becomes ever more valuable. Air blown fibre delivers exactly that capability.