Avionics News June 2022 - 23

" THE WORST CASE (FOR 5G INTERFERENCE)
IS REALLY FOR HELICOPTER OPERATORS,
SINCE IT'S EASY TO LIMIT THE
INTERFERENCE AROUND AIRPORTS
WITH INSTRUMENT LANDING SYSTEMS,
NOT SO EASY EVERYWHERE A MEDICAL
HELICOPTER MAY NEED TO LAND. "
- Andy Thurling, chief technology officer at NUAIR
n the nation's capital, things can go awry when federal
agencies are still figuring out how to avoid radar
altimeter interference as the big telecom companies
roll out the latest in 5G cellphone technology. Former Federal
Aviation Administrator Steve Dickson told the U.S. House
Subcommittee on Aviation in February that the agency and
aviation industry cautioned the Federal Communications
Commission about possible 5G interference with radar altimeters
in 2018 and supported related research efforts.
Dickson and the Department of Transportation asked the
I
National Telecommunications & Information Administration in
December 2020 to delay auctioning spectrum adjacent to where
radar altimeters operate. The FAA urged the FCC to exercise
caution and in December 2020 provided studies to back up its
concerns on aviation safety. The auction went ahead, and Verizon
and AT&T scheduled initial 5G deployment for December 2021.
When it became clear the new service would interfere with
some radar altimeters of aircraft operating into airports near 5G
towers, the FAA and Department of Transportation asked for
and obtained relief. There were two pauses in which Verizon and
AT&T kept some towers turned off.
The FAA received data from the wireless companies on
transmitter location, power level and signal shape to conduct
a safety assessment and set new standards for altimeter
performance. Then in February, the FAA issued airworthiness
directives revising landing requirements for a wide range of
Boeing and Airbus aircraft. In the airworthiness directives, the
FAA noted, for example, that several systems on a 737 rely
on the radar altimeters including autothrottles, GPWS, thrust
reversers and TCAS.
Dickson, who retired March 31 and was succeeded by
Acting FAA Administrator Billy Nolen, believed that by
working together in a collaborative way with industry,
aviation and 5G can safely coexist.
Another way to look at these issues is that the
telecommunications companies acquired the spectrum
from the FCC and are operating within the confines of the
spectrum acquired.
" This is a typical classical radio engineering issue that hasn't
got a thing to do with 5G, " said Patrick Diamond, a telecom
consultant who is a board member on the National Space-Based
Position and Timing Advisory Board.
5G uses a number of bands that are 100 megahertz wide from
the lowest frequency of 640 MHz to the highest that Verizon
and AT&T use, which is millimeter wave at 39 gigahertz. This
high frequency is used on the network to transmit data bursts
over short distances - only 35 to 40 feet apart. The telecom
companies wanted these frequencies because they can carry a lot
of data, thereby allowing 5G to download at 1 terabit per second.
Michael Koziol, IEEE Spectrum associate editor, wrote on
Jan. 20 in an article titled " What you need to know about the
FAA 5G kerfuffle (Why is 5G only a problem in the U.S.?) " that
avionics news * june 2022 23
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