As 5G rollout begins, Pentagon still doesn’t understand impact on military aircraft

WASHINGTON: Today, after multiple delays and months of negotiations with the airline industry, Verizon and AT&T will begin rolling out 5G nationwide, in a move the commercial aviation community says will have dire safety implications.

Airline executives warned in a Jan. 18 letter that, without safeguards in place around airports and runways, the rollout could cause “catastrophic disruption” and “economic calamity.” Despite an agreement by Verizon and AT&T on late Tuesday to limit 5G services around major airports to prevent interference, some international airlines such as Emirates and Lufthansa canceled flights to the United States due to concerns about potential effects on the Boeing 777.

But for a controversy that’s dominated headlines and reached the desk of the president, the Pentagon — the largest aircraft fleet owner in the world — has remained largely silent. That’s because right now, it doesn’t know how 5G will affect military aircraft.

All told, it will be at least a year and a half after the Federal Communications Commission began selling spectrum for 5G before the Defense Department weighs in on the issue, and it could take months after that for the department to come up with a plan to resolve any technical failures that occur as military pilots continue flying in areas where the 5G deployment is occurring.

The overarching problem shared by both the military and civil aviation revolves around radar altimeters, a piece of hardware used by airplanes, rotorcraft and even some drones to measure the height of an aircraft from the ground.

In the United States, 5G will reside on a neighboring portion of the C-band spectrum to radar altimeters. Some aviation experts and government officials are concerned that the resulting interference could prevent aircraft from being able to make landings in bad weather — or worse, that pilots may not truly understand an aircraft’s distance from the ground, increasing the risk of a crash.

RELATED: Pentagon kicks off spectrum sharing experiments in Utah

“The DoD continues to work very closely with our FAA counterparts on this issue. All DoD Services issued bulletins to the field/fleet, making aircrews aware of the potential for interference and establishing a mechanism to report instances of interference,” said Lt. Col. Dylan McDermott, the Pentagon’s point person on this issue in his role as head of the Aviation Cyber Initiative, co-chaired with the FAA and Department of Homeland Security.

While military pilots will be advised of the potential issue, the department has not issued any NOTAMS — a “notice to air missions” that spells out hazards and or other abnormalities in the air — for any of the military bases in 5G deployment areas, McDermott said in a Jan. 18 statement to Breaking Defense.

However, NOTAMs issued by the FAA will also apply to military aircraft during operations from civil airfields, he said. Some of that guidance, published by the FAA last week, prohibits pilots at certain airports from making “instrument landings” — a landing where visibility is low due to weather or other factors, and a pilot relies on avionic systems like radar altimeters — in areas where 5G interference is a possibility.

So what does that mean for the military? It’s hard to say.

On Monday, the FAA approved two currently-in-use altimeters for low-visibility landings at 48 of the 88 airports that could be impacted by 5G interference. These two models are already installed on 45% of the commercial aviation fleet, including in aircraft such as the Boeing 737, 747, 757, 767 and MD-10/-11.

Many US military aircraft are derived from those commercial designs, and if they share the same altimeters, could essentially operate as usual from both military and civil airfields. Those aircraft include the Navy’s P-8 Poseidon, based on the Boeing 737; the E-4 Nightwatch and VC-25A — also known as Air Force One when the president is onboard — both of which are based on the Boeing 747; the C-32 executive transport plane, based on the 757; the KC-46A tanker, based on the 767, and the KC-10 tanker, based on the MD-10.

Boeing declined to comment on whether these military derivatives would also be cleared for instrument landings at commercial airports. In a statement to Breaking Defense today, US Transportation Command said that it has not yet experienced any impact to is aviation missions due to the 5G rollout, and that it “is aware of and is closely monitoring, via the FAA, the 5G rollout and its impact to aviation.”

For other military aircraft models, flying out of civil airports could get more difficult when bad weather strikes, as pilots unable to make instrument landings may be forced to land at neighboring airfields or cancel flights in order to abide by FAA guidance. While that might not be a problem for all squadrons, it could adversely affect military airfields that are collocated with civil airports, such as Portland International Airport, which is used by the Air National Guard.

It’s also unclear how the potential interference could impact aircraft that frequently are flown at low altitudes, such as helicopters or planes used by special operators like the AC-130, which could be more at risk of a crash if radar altimeters are no longer giving accurate readings to pilots.

In The Public Fight Over 5G, Pentagon Largely Absent

While the Federal Communications Commission and FAA have waged a yearlong public battle over the 5G rollout, the Defense Department has played mostly a silent, tertiary role as officials attempt to better understand the issue while remaining behind the scenes.

RTCA, a trade organization that works with the FAA on safety standards, published a Oct. 2020 report raising concerns about the potential for 5G interference to radar altimeters, “including the possibility of catastrophic failures leading to multiple fatalities, in the absence of appropriate mitigations.” However, that report only measured the impact of 5G on commercial altimeters.

In January 2021 — a month after the FCC had begun auctioning C-band spectrum in the 3.7–3.98 GHz frequency for 5G —  Pentagon officials told Defense News that the department would not try to slow down 5G deployment. Instead, officials hoped to conduct their own testing of military radar altimeters before laying out a plan to mitigate any risks.

This stance did not change as President Joe Biden took office. The Biden administration has remained broadly supportive of the 5G rollout while commending efforts to address concerns from aviation authorities.

In a Jan. 18 statement issued after Verizon and AT&T agreed to delay the 5G rollout around airports, Biden said the move “protects flight safety and allows aviation operations to continue without significant disruption and will bring more high-speed internet options to millions of Americans. Expanding 5G and promoting competition in internet service are critical priorities of mine, and tomorrow will be a massive step in the right direction.”

Meanwhile, the Defense Department has made quiet progress in its efforts to better understand how military aircraft could be impacted. In April 2021, the Pentagon, FAA and DHS funded their own evaluation centered around military aircraft: the Joint Interagency 5G Radar Altimeter Interference Quick Reaction Test.

“What we were chartered to achieve was to provide validated 5G test methodologies,” said McDermott in a Jan. 13 interview. “Our intent with that is to support some follow-on testing [and get] some insight into possible mitigations and standards.”

The test involves a two-step approach. First, the department is working with the nonprofit MITRE Corp to create methodologies and 5G waveforms that can then be used to conduct bench tests of altimeters.

“We have a number of radar altimeters that are already on the bench,” said McDermott, who added that the hope is to test enough altimeter models to cover at least 80% of aircraft used by the US military.

Then, military aircraft — as well as commercial aircraft used by the Civil Reserve Air Fleet — will go through live tests at Hill Air Force Base in Utah or Majors Airport in Texas. During those flights, aircraft and helicopters will conduct instrument approaches and low level approaches in the presence of a 5G tower to see whether the 5G signals trigger interference. (McDermott could not immediately specify which telecom providers would be partnering with the department for tests.)

The team hopes to have all testing and analysis done by the end of the summer, he said.

“Through the course of our trials, you know, we’ll get a pretty good sample of what individual radar altimeters will or will not do in the presence of 5G,” he said.

However, when asked whether the conclusion of the study would give the department the information it needed to mitigate any interference or technical problems found during testing, McDermott acknowledged that recommending an action plan is not one of the objectives of the test team.

That means it could take even longer for the Pentagon to assess whether existing altimeters need to be modified or replaced by new models and to determine the total cost to the department.

“At the end of this, will there be additional work?” McDermott said. “Yes.”

Honeywell, one of the two major domestic producers of altimeters and an early participant in Pentagon discussions, said in a statement that the company is closely following the issue.

“If needed, we’re ready to verify compatibility of our equipment with any new requirements and we have been working with the FAA, Department of Defense and aircraft manufacturers to conduct testing of our systems in the 5G spectrum,” Honeywell spokesman Adam Kress said, adding that the company has yet to receive additional requirements for their altimeters from the FAA or aircraft manufacturers.

Collins Aerospace, the other main supplier, declined to comment for this article.