Imagine you’re on a long-haul flight from London to Johannesburg. The pilot depends on seamless satellite communications for weather updates, navigation and communication with ground control. Suddenly a signal disruption caused by mobile broadband interference scrambles crucial data. The aircraft loses navigation accuracy, forcing the crew into emergency procedures to avoid disaster.

This scenario underscores the potential for disaster if the resilient L-band satellite communications link is not protected, ensuring that air travel remains safe and dependable and preventing worst-case scenarios.

Lost at sea

A fishing vessel off the Cape coast encounters a severe storm. The crew activates their emergency distress beacon, sending a signal via satellite to the rescue coordination centre. But interference from newly deployed mobile communication services scrambles the signal, delaying emergency response. In a situation where minutes can mean the difference between life and death, safeguarding the L band ensures seamless emergency communications and saves lives at sea.

A city cut off

A powerful earthquake hits a remote town in South Africa, taking down all terrestrial communication infrastructure. Emergency responders rely on satellite-based communication systems operating in the L band to coordinate relief efforts. However, interference from IMT services renders these satellite links unreliable, delaying crucial medical aid and supply chains. Ensuring interference-free L-band communications means communities can stay connected when most needed.

A cybersecurity breach in national defence

South Africa’s military operations depend on secure satellite communications for intelligence gathering and strategic coordination. A cybercriminal group or foreign entity exploits the weakened L-band spectrum due to unchecked IMT expansion, causing disruptions in encrypted defence communications. The inability to coordinate effectively puts national security at risk. By protecting this spectrum, South Africa ensures that its defence forces remain operationally ready and secure.

These examples highlight the criticality of the satellite communications links in the L-band spectrum at 1 500MHz.

Read: Cell C surrenders spectrum licences to Icasa

Managing this radio spectrum is a crucial aspect of national telecommunications policy, balancing the needs of essential safety-of-life applications and commercial mobile broadband services. As communications regulator Icasa considers extending International Mobile Telecommunications (IMT) operations into the 1 492MHz to 1 518MHz spectrum band, industry experts and stakeholders warn of significant risks to existing aviation, maritime, satellite and national security services. The urgency of preserving the integrity of the L band is not just a technical necessity but a matter of public safety and economic stability.

The importance of the L band

The L band (between 1GHz and 2GHz) has long been a critical resource for satellite communications given the band’s propagation characteristics and its resilience to operate in any climatic conditions. It is used for essential services including:

Aviation safety: Air traffic management and navigation rely on adjacent frequencies for safe and efficient air travel.
Maritime operations: The Global Maritime Distress and Safety System (GMDSS) ensures ships at sea maintain reliable distress communications.
Land mobile services: Providing emergency response, disaster relief and rural connectivity across Africa.
National security: Defence communications operate in adjacent bands, and interference could compromise mission-critical operations.
Scientific and environmental monitoring: The L band supports key scientific applications, including weather monitoring, Earth observation and climate research, which could be severely impacted by spectrum congestion.

These services depend on an interference-free environment, and Icasa’s proposal to extend IMT services beyond 1 492MHz could risk disrupting these essential operations.

Risks of extending IMT beyond 1 492MHz

1. Aviation and maritime safety at risk

As a signatory to the International Civil Aviation Organisation (ICAO) and the International Maritime Organisation (IMO) agreements, South Africa must ensure that its spectrum policies do not endanger aviation and maritime safety. The 1 518MHz band is used for aircraft telemetry, navigation and control, and extending IMT to 1 518MHz could introduce harmful interference, leading to flight delays, communication failures and increased accident risks.

Similarly, the maritime sector depends on L-band frequencies for distress signals and emergency communications. South Africa’s Rescue Coordination Centre covers vast maritime zones, and interference in this spectrum could hinder emergency response operations, endangering lives at sea.

2. Disrupting satellite-based emergency and rural connectivity

Satellite operators rely on L-band frequencies to provide uninterrupted communication services in remote and underserved regions. In disaster scenarios, these services are crucial for coordinating rescue operations and ensuring connectivity when terrestrial networks fail. Interference from IMT services beyond 1 492MHz could degrade these vital services, leaving vulnerable communities at risk.

3. Economic and strategic consequences

The economic ramifications of disrupting L-band satellite services extend beyond safety concerns. Sectors such as mining, agriculture, logistics and aviation depend on seamless satellite connectivity for operations. South Africa also risks non-compliance with global spectrum management frameworks, potentially impacting trade relations and international cooperation.

Additionally, countries that have assigned spectrum without thorough impact assessments have faced severe economic consequences due to service disruptions, costly mitigation efforts and increased regulatory disputes. A premature shift to IMT in this band could necessitate expensive interference mitigation solutions, placing unnecessary financial burdens on affected industries.

4. National security implications

Defence agencies also use the L band for encrypted communications, remote operations and intelligence gathering. Allowing IMT services to extend beyond 1 492MHz could create vulnerabilities in national security communications, potentially exposing critical systems to signal degradation or unauthorised access. Given South Africa’s role in regional peacekeeping and security coordination, maintaining an interference-free L band is vital for operational readiness and national sovereignty.

Conclusion

While mobile broadband expansion is essential for South Africa’s digital economy, it must not come at the cost of aviation safety, maritime security and satellite reliability. Icasa should maintain the IMT spectrum cap at 1 492MHz to protect critical services, ensure regulatory alignment with international standards and safeguard national security.

The author, Wydeman Coetzee, is founder and managing partner at Global Policy Partners. GPP is holding a one-day seminuar in Sandton on Tuesday, 25 March 2025 to discuss the risks of extending IMT services beyond 1 492MHz and explore alternative solutions

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