It's very hard to know, at this point, whose concerns are valid and whose problem this ultimately is, but a battle continues playing out between telecom companies, the FAA and the airline industry over a planned rollout of 5G wireless service — and it's coming to a head on Wednesday.

First off: What is behind the freakout?
The arrival of high-speed 5G or fifth-generation broadband cellular networks has been discussed and expected for years now, and the U.S. is actually behind some other nations in the rollout of 5G service. And while AT&T and Verizon offer some 5G service in some locations, this has been limited and slow due to bandwidth — with both companies banking on new C-band frequencies, purchased at auction from the FCC, to provide true high-speed service. One reason for the delay has been the vociferous pushback from airlines which say that the C-band frequency spectrum used by 5G towers is too close to the radio frequencies used by airplane altimeters (the gauges that measure a plane's altitude) — and they are concerned that interference will compromise the safety of planes taking off and landing at airports, with airplane systems and pilots potentially making serious errors in low-visibility conditions.

AT&T and Verizon, which were expected to roll out their full 5G service on Wednesday following multiple delays, say that the airlines' concerns are unfounded — and that 5G has already rolled out in France and the UK without incident. The FCC backs them up, and both argue that the C-band frequencies used by 5G are far enough apart from those used by altimeters to avoid interference.

Why is this happening this week?
The airlines have been pushing to delay the wider 5G rollout for months now, and a final two-week delay was agreed upon on January 3, until January 19, in order to make final assessments about altimeter interference.

Despite that agreement, as Reuters reports, the CEOs of all major U.S. airlines penned a letter Monday to Transportation Secretary Pete Buttigieg warning of "catastrophic" impacts on cargo and air travel this week if the rollout occurred as planned.

Both AT&T and Verizon have spent billions to acquire these frequencies and have been very eager to begin offering the high-speed service promised to consumers — and in an indication that they acknowledge some of the airlines' concerns, AT&T at least just purchased more of these "mid-band" frequencies in a range that is further apart from that used by the airplane equipment.

In response to the latest pushback, on Tuesday, AT&T and Verizon announced that they would "voluntarily" and "temporarily defer turning on a limited number of towers around certain airport runways" in order to appease the airlines and ease the transition — but this did not appease two international carriers, Emirates and Air India, which are suspending flights this week into multiple U.S. airports.

The FAA may be partly to blame for the slow rollout
The airlines' last-minute freakout may be in response to the fact that, just on Sunday, the FAA said it had cleared 45% of the nation's commercial plane fleet to perform landings safely under new procedures for low-visibility conditions in areas where 5G interference could be of concern. Among the plane types not yet cleared are Boeing 777s and 787s, which may be the reason why a carrier like Emirates is balking, and both United and American also have dozens of 777s in service, as the New York Times notes.

There are technical arguments being hashed out about how the 5G rollout was different in France versus what is happening in the U.S., and whether certain scenarios will lead to planes malfunctioning or catastrophic errors, and this is where it's not clear if airlines are being overly alarmist or if the alarm is valid.

A wireless industry group, GSMA, issued a statement to the Times saying, "In our opinion, the technical information that is being used to generate concern shows improbable worst-case scenarios."

How will this impact travel at SFO?
It's not clear whether SFO is one of the airports where the telecoms have agreed to a temporary two-mile radius where towers won't be fully powered up. But what is clear is that the confusion could result in delays or cancelations for some long-haul international flights — and if you were booked on Air India or Emirates this week you likely have already had your flight canceled.

Emirates is also suspending flights to eight other U.S. airports: Boston, Chicago, Dallas-Fort Worth, Houston, Miami, Newark, Orlando, and Seattle. In a statement today, the airline vaguely cites "operational concerns associated with the planned deployment of 5G mobile network services" and says that flights are suspended until further notice.

David Seymour, the CEO of American Airlines, issued a letter to all company employees Tuesday warning of "major operational disruptions" when the rollout occurs, though it remains unclear what these will be.

"To be very clear, we’re incredibly disappointed that we are at this point, that the entire U.S. airline industry is facing major disruption as new wireless technology is activated," Seymour wrote. "The two should be able to coexist, but that only comes with better understanding of potential impacts."

Photo: Duke Cullinan