The Enigma of 5G and Aircraft Altimeters: An Inside Look at the FCC Approval

One of the perennial questions surrounding the rollout of 5G technology has been its supposed interference with aircraft altimeters. While the Federal Communications Commission (FCC) has given the go-ahead for the technology, the reasoning behind this decision remains complex and often misunderstood. This article aims to dissect the issue, examining the technological and regulatory context, and considering alternative interpretations.

Historical Context: Altimeters in the 1960s

The radar altimeters used by airlines today were designed in the 1960s when they had exclusive access to the C-band. At that time, adjacent-channel interference was not a design issue. This historical context highlights the regulatory landscape in which these devices were originally designed, making the current situation more nuanced.

Regulatory Allegiances and Promises

Cellular developers have made promises that 5G technology would not interfere with appliances like WiFi. However, it appears that these promises have not been fully embraced by the radio engineer community. The fact that adjacent channels are only a couple of hundred megacycles apart has raised concerns among engineers about the potential for interference.

It is important to note that while the FCC regulates transmitters, receiver designers are left to make their own choices. They must balance cost and performance, often making educated guesses about future spectrum allocations. In this case, it seems that some receiver designers were persuaded by promises from 5G advocates, leading to the approval of the technology without sufficient safeguards for legacy equipment.

The European and Asian Perspective

It is notable that in regions such as Europe and Asia, 5G has been deployed without significant issues affecting aviation. This suggests that there may be differing regulatory approaches or less stringent requirements in these areas. However, this does little to address the concerns raised in the U.S. and raises questions about the global standards for 5G.

Cost and Interference Trade-offs

The cost of implementing new altimeter designs that can withstand the C-band interference is a critical factor. Receiver designers must weigh the costs against the risks. Upgrading existing 5G infrastructure to avoid interference is costly, making it a contentious issue. Thus, the debate centers around who should bear the cost of these upgrades, with various parties seeking solutions that shift the financial burden.

Lessons from the GPS Saga

A similar controversy occurred with LightSquared and GPS. The GPS receiver designers had already made decisions based on existing spectrum allocations. When the FCC attempted to reallocate spectrum, it led to public outrage when it appeared that GPS functionality was being compromised. This incident highlights the challenges in making such changes without causing significant disruption.

One potential solution is to create a market for guard bands where transmitter and receiver manufacturers can negotiate. This idea could provide a balanced solution, but it is fraught with logistical challenges. Ensuring that the negotiations are fair and that all stakeholders are adequately represented is a critical hurdle.

Conclusion and the Call for Transparency

While the FCC has approved the release of 5G technology, there remains a need for transparency and evidence-based claims about the potential issues with aircraft altimeters. Without a clear understanding of the risks and the potential impact, stakeholders are left to speculate. It is essential for the tech industry, regulatory bodies, and the public to work together to ensure that these concerns are addressed through rigorous testing and transparent communication.

In summary, the approval of 5G technology for use in the U.S. amid concerns about potential disruption to aircraft altimeters is a complex issue. Understanding the historical context, regulatory landscape, and potential alternatives can help in forming a more informed opinion. As the technology continues to evolve, it is crucial to maintain a robust dialogue to address these concerns.