Concerns over possible interference between mid-band 5G and aviation altimeters has caused Verizon and AT&T to delay their 5G deployment.

Verizon and AT&T recently spent billions to acquire mid-band spectrum, specifically the C-Band, in the 3.7 to 3.98 GHz range. The spectrum is considered the sweet spot for 5G, offering a combination of speed, range and building penetration. Unfortunately, radar altimeters run in the 4.2-4.4 GHz range, making them dangerously close to the C-Band spectrum.

The Federal Aviation Administration (FAA) has voiced concern over whether a nearby cell tower could negatively impact altimeters, potentially causing major safety issues for the airline industry.

As a result of the concerns, both Verizon and AT&T have pushed back deployment of their C-Band spectrum by a month, to allow time to address the concerns.

The big winner in the entire situation is T-Mobile. While the second-largest carrier bought some C-Band spectrum at the latest auction, the bulk of its 5G spectrum is in the 2.5 GHz range, far enough for there to be no concerns about interfering with altimeters.

Some experts are already predicting the month-long delay on the part of Verizon and AT&T will only serve to help T-Mobile grow its 5G lead even more.