5G doomsday never came, but US airlines are not out of the woods yet

Last Monday, it sounded as if the U.S. aviation system faced imminent doom due to the activation of 5G C-band cell phone service.

“Immediate intervention is needed to avoid significant operational disruption to air passengers, shippers, supply chain and delivery of needed medical supplies," airline executives said in a letter to the Biden administration. A separate statement from United Airlines warned of even more dire consequences.

On Tuesday, Verizon and AT&T, the two operators of 5G C-band service, agreed to keep the service turned off near airports.

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Not even an hour later, a number of foreign Boeing 777 operators, including Emirates and All Nippon Airways, said that they would not fly the plane to the U.S. But by last Wednesday, the issue appeared to have been mostly resolved on a large scale. It wasn't the end of the issue, though.

The U.S. aviation system entered its second week of the 5G C-band era on Wednesday with significant progress made in clearing planes to fly amid the 5G rollout — but not before some disruptions continued to affect certain operators.

The Federal Aviation Administration on Tuesday said that it had granted equipment approvals to the radio altimeters found in approximately 90% of the U.S. commercial airline fleet. A radio (or radar) altimeter is a type of instrument that is used to precisely measure an aircraft’s height above the ground. This type of instrument is essential during low-visibility conditions because the data from it is essential for pilots to be able to conduct high-precision instrument approaches and even automatic landings, allowing operations to continue in little to no visibility. In certain types of aircraft, other systems use radio altimeters and have shown susceptibility to 5G interference.

But the FAA's approvals are not as sweeping as it may sound, and it is up to individual airlines to take the steps necessary to allow for low-visibility operations at airports affected by 5G. At at least two airlines that operate the popular Airbus A320 family, some aircraft have been cleared, while others still await clearance, according to pilots familiar with the matter.

More: What you need to know about 5G interfering with aircraft

And while there have been no large-scale disruptions in the past week, individual airports experiencing low-visibility conditions — or ones that have unique operating conditions — have seen delays, cancelations and diversions due to 5G.

Last Thursday, flights operated by regional carrier SkyWest and other airlines were seen in holding patterns near San Francisco International Airport (SFO), with some flights diverting to other airports, as other, approved aircraft were seen landing normally. In a statement, SkyWest attributed the issue to 5G interference.

In some of the more unusual 5G-related disruptions, flights from Key West (EYW) to the New York area operated by Republic Airways for United and Delta Air Lines were forced to make fuel stops at other Florida airports after departing the airport's short runway due to an aircraft warning system that was impacted by 5G, according to a pilot familiar with the matter. By the beginning of this week, flights appeared to be operating normally again.

On Saturday, low-visibility conditions at Seattle-Tacoma International Airport (SEA) cost airlines nearly $150,000 in delays, according to an analysis by Tim Donohue, who writes Aerology, which analyzes flight delays.

Two days later, all of Monday's commercial flights at Paine Field (PAE), north of Seattle, were also canceled due to low-visibility conditions and 5G. "This is out of our control, and we are as frustrated as you are," the airport tweeted from its official account.

And on Tuesday, the FAA issued an airworthiness directive that appeared to restrict 777 operations, along with the 747-8, though an agency spokesperson downplayed the issue to TPG.

"If you're operating into an airport that has an AMOC, it doesn't apply," the spokesperson said, using the acronym for an alternative method of compliance, the mechanism that the FAA uses to approve aircraft for 5G operations.

And while progress continues to be made with the FAA's approvals, the agency stressed last week that some aircraft might not be approved in the end.

"We anticipate some altimeters will be too susceptible to 5G interference," a statement last week said.

One important aircraft type that has yet to be approved is the Embraer Regional Jet, also known as the Embraer 135/140/145. The ERJ operates regional flights for American Airlines and United, and also flies for smaller carriers like Denver Air Connection, aha! and JSX.

With no approval timeline for this aircraft type, travelers flying on this model might run into delays or cancellations at airports that are prone to low-visibility conditions.