Why Foreign Airlines Grounded Aircraft as 5G Went Live: The Role of Radar Altimeters and CYA

The recent decision of foreign airlines to ground their aircraft in cities where 5G services were about to be rolled out is a complex issue that highlights the intricate intersection of the aviation and telecommunications industries. This article seeks to explore the technical and legal background of this issue, focusing on the involvement of radar altimeters and the principle of ldquo;CYArdquo; (cover your ass).

The Technical Challenge

As new 5G frequencies were set to be turned on, several foreign airlines took the precautionary measure of grounding their aircraft in various cities. This decision was made out of concern that the new 5G frequencies could interfere with aircraft instruments, particularly radar altimeters. Radar altimeters are critical for determining an aircraft's altitude, especially during low-visibility landings.

In the United States, specific frequency bands used for 5G are close to those utilized by some radar altimeters. This proximity led to fears that 5G signals could potentially cause interference, which in turn prompted airlines and aviation authorities to take precautionary measures, including grounding flights or rerouting them to ensure safety.

Regulatory Measures and Coordination

Regulatory bodies like the FAA in the U.S. have worked closely with telecommunications companies to mitigate these risks through a series of measures. These include setting up buffer zones around airports and ensuring that 5G towers are not operating at full power near key flight paths. These actions underscore the importance of coordination between the aviation and telecommunications industries to ensure safety while expanding wireless technology.

The Role of Radar Altimeters

At the heart of this debate are radar altimeters, which have been in use since the 1960s. These instruments measure the distance between the aircraft and the ground, playing a crucial role during low-visibility landings. The design of these instruments was made without considering terrestrial users of the C-band, as the FAA does not regulate nor care about receivers, only transmitters. This oversight meant that these instruments were more cost-effective but have now become a source of concern.

The U.S. carriers, particularly the budget airlines, are still primarily using older radar altimeters. These instruments can be essential for performing Class-II instrument approaches, which can go as low as 100 ft without needing a visual of the runway. In comparison, Class-I approaches can only go down to 200 ft. Thus, if the aircraft is not equipped with a radar altimeter, only a Class-I approach is available.

The Legal Angle: CYA

Underlining the importance of these actions is the principle of CYA, or cover your ass. If the FAA indicates that there might be a problem, lawyers are likely to take the position of defensive crouch, waiting for specific OKs from the FAA before continuing operations. While this seems excessive, it is a common practice in aviation law where any accident involving an instrument approach could result in lawsuits.

When the FAA suggests that CAT-II approaches could be compromised by cellular communications on adjacent C-band channels, it can become a win for plaintiff attorneys. Even if the actual operation was not performing a CAT-II approach, the potential risk is enough to invoke CYA mode.

This underscores the delicate balance between technological advancement and safety, and it also highlights the significant impact that regulatory bodies like the FAA have on the decisions made by airlines and the broader aviation community.

In conclusion, the grounding of aircraft due to 5G concerns is a multifaceted issue that bridges the gap between technical safety, regulatory oversight, and legal protocols. While the practical and legal reasons for grounding are clear, it also raises broader questions about the balance between technological progress and aviation safety.

Keywords: 5G interference, radar altimeters, safety measures, CYA, airline grounding