As any frustrated mobile phone user without a decent connection can attest, 5G (fifth generation) technology for mobile phone networks will bring tremendous benefits to society thanks to download speeds that are almost 200 times faster than 4G. We promise you profitable profits. In recent years, the rapid rollout of 5G in the United States has seen tens of thousands of new masts sprout in cities across the country.
This poses a potential problem for aviation, especially if the mast is close to an airport. Interference from 5G networks can “confuse” low-range radar altimeters, a critical part of the avionics that tells pilots the exact altitude, especially during final approach. This is done by “reflecting” the signal off the ground and other obstacles such as trees and buildings.
Radar altimeters have used the internationally recognized 4.2-4.4 GHz band since they began being deployed on commercial aircraft in the 1970s. However, with the arrival of 5G in 2019, the Federal Communications Commission began allocating portions of the adjacent 3.7 to 4.2 GHz band to carriers. This created the potential for harmful radio frequency interference.
Although current telecommunications utilization of C-band frequencies is currently considered manageable, the potential for increased usage poses even greater challenges. From now until 2028, slots could be allocated to up to 19 more telecommunications providers, and the resulting congestion increases the likelihood of radar altimeter interference during critical stages of flight.
Because radar altimeters are usually very accurate, there is little need to elaborate on the effects of erroneous readings during critical flight phases, especially when no other clues exist for the pilot, such as bad weather. Other safety-related onboard sensors, such as the Terrain Avoidance Warning System (TAWS), also rely on radar altimeter.
Other important safety features that can be affected by erroneous readings from the radar altimeter include auto spoilers and thrust reversal devices. These drag devices tend to deploy automatically upon landing, using a steadily descending altimeter to verify the signal from the wheel weight sensors.
The reason auto spoilers and thrust reversers do not rely solely on wheel weight switches is to ensure that they do not activate during flight if the sensor fails. However, if the radar altimeter also provides incorrect information, the aircraft may interpret the correct wheel weight signal as invalid.
For carriers, one solution may be to simply avoid airports where there is a risk of interference from 5G masts. Fortunately, another option is less confusing. Manufacturers of radar altimeters, such as industry leader Collins Aerospace, his RTX company, can deploy quick and easy solutions to block signals that can interfere with altimeter functionality.
Since February 1, the Federal Aviation Administration has required passenger and cargo airlines, known as Part 121 carriers, to replace or update their altimeters so they can safely operate near 5G radio signals. Collins has spent much of 2023 working at “breakneck speed” to ensure compliance for commercial customers, said Mark Ayala, senior director of business and regional avionics sales.
On the business aviation side, the situation is different. Although the FAA has identified risks to Part 91 or Part 135 operators, it has stopped short of mandating the same amendments as for commercial operators. For this reason, most business aircraft owners or aviation departments have not yet chosen to adapt radar altimeters.
Mr Collins wants to change this and has made a two-part appeal to the business aviation community. Collins reminds operators of the importance of avionics safety, which is “often taken for granted,” and highlights how easy it is to update radar altimeters during regular hangar visits. are doing. “The paperwork takes longer than the actual exchange,” Ayala says.
Collins’ ALT 4000 is the most widely used radar altimeter in business aircraft. The altimeter’s successor, the ALT 4000+, comes with an internal filter that removes energy from adjacent bands such as 5G signals, and Collins says it can be used as a partial replacement for existing equipment or as a service bulletin upgrade. We are proposing to install this filter as part of the installation.
Following regulatory approval of the ALT 4000+ in the middle of last year, Collins is now implementing a series of STCs. [supplemental type certificates] Covering a wide range of business aircraft types, we can ‘plug and play’ replace traditional equipment in a matter of hours.
Collins’ solution is targeted at the United States, but the company is considering offering it in other markets where 5G networks are deployed. However, the needs may also be different if the government allocates different bands to his 5G operator or simply has a different mast design. For example, in Europe, antennas tend to be installed at an angle to the ground, so the risk of interference is lower.
One of the challenges Collins faces in the United States is complacency about the dangers of 5G. “People will say, ‘He has 5G service on my phone and I’ve never had a problem,'” Ayala points out. “It has nothing to do with having a cell phone in your pocket. What we’re concerned about is interference from transmitters on the ground.”
Similarly, Ayala is keen to emphasize that the bad guy is not 5G itself. “With RTX, he is embracing 5G for all kinds of applications,” he says. “This is a very specific issue with the transmitter. There is no problem with having other of his 5G products in the cockpit.”
