Aircraft incidents and accidents are complex. When one occurs,
it can involve a multitude of factors such as human error,
organizational problems, and/or environmental factors. Recently, a
new risk factor related to technological advancement has formally
been introduced to the aviation industry. This risk factor is 5G
wireless technology.
What is 5G?
5G is an invisible but critical force in our lives these days.
The radio frequency spectrum supports our reliance and dependency
on wireless communications and radio frequencies are key for
business, personal cell phone use, and for autonomous technology
and aviation.
Radio waves travel across the electromagnetic spectrum, and this
spectrum is comprised of frequency bands. The spectrum bands are
similar to a multi-lane highway, but with each lane having its own
unique characteristics. These characteristics specify who can
operate within that lane or spectrum band, and some bands are
licensed. In Canada, the department of Innovation, Science and
Economic Development manages the spectrum and in the United States,
the Federal Communications Commission (FCC) is in charge of the
spectrum.
5G is the fifth generation of wireless communication, opening up
a new "highway lane" for increased connectivity, response
time and bandwidth. The first generation (1G) was introduced in the
early 1980s and led to wireless telephones that were able to
transmit audio only. Technology advanced through to 4G, increasing
our connectivity over time. The 5G network will set a new pace for
business and communication.
5G communication operates within the 3.7-4.2 GHz frequency band.
A portion of this band, specifically the portion designated as
3.7-3.98 GHz frequency, will be dedicated to 5G (sometimes referred
to as the C-band). Traditionally the C-band does not have high
traffic given its current occupation by low-powered satellite
operation. However, that is changing and the C-band could
eventually get very busy.
With the development and adoption of any new technology,
discerning what is a conspiracy theory from what is a real threat
can take time. Over the past few years (notably in late 2020 and
early 2021), alarm bells from reputable sources are ringing about
how the introduction of 5G could negatively affect the safety of
low-level aviation operations.
Radar altimeters
To understand the issue, we have to first identify the avionics
that raised the alarm bells about aviation safety.
An altimeter is the only instrument within an aircraft that
allows the pilot to know how far above the ground or obstacles they
are. The altimeter measures the distance between the aircraft and
the ground using radio frequencies in the "highway lane"
just above the 4GHz range. An altimeter is a key instrument used
for take-offs, landings and low-altitude flying and can also
provide critical input to other aircraft systems, such as
traffic-alert collision avoidance systems (TCAS). Commercial
aircraft, civil aircraft, military aircraft, helicopters, (and some
UAVs) all have altimeters.
Radar altimeters operate in the 4.2-4.4 GHz space, just above
the C-band intended for 5G.
Inaccurate altimeter readings can result in a significant and
dangerous problem for the pilot, the aircraft, and any
passengers.1
The RTCA report and the risk to aviation
The Radio Technical Commission for Aeronautics (RTCA) is a
private, not-for-profit association. The RTCA works regularly with
the government for aircraft equipment certification, and in the
development of aviation industry standards for regulatory
compliance.2
On October 8, 2020, the RTCA distributed a 231-page publication
of its study that evaluated how 5G emissions could interfere with
an aircraft's radar altimeter performance.3 The
publication was in response to the anticipated expansion of the 5G
C-band. To date, the RTCA publication is the most comprehensive
analysis on this topic.
The results of the RTCA's testing and evaluation, and
contained in its peer-reviewed publication, reveal "a major
risk that 5G telecommunication systems in the 3.7-3.98 GHz band
will cause harmful interference to radar altimeters on all types of
civil aircraft – including commercial transport airplanes;
business, regional, and general aviation airplanes; and both
transport and general aviation
helicopters."4 The 5G interference could
result in inaccurate altimeter readings, or complete altimeter
failure, resulting in pilots being unaware of their distance from
the ground.
Within the analysis contained in the October 2020 RTCA
publication, an example landing approach at Chicago's
O'Hare Airport is used. The RTCA adopted a precision approach
to Runway 27L, as this is the "single most utilized runway for
arrivals at O'Hare".5 The RTCA also
assumed locations of 5G base stations based on the locations of
five existing 4G base stations already within or near the approach
path to Runway 27L. The RTCA then assessed the risk of 5G
interference on an aircraft's descent to Runway 27L. The RTCA
found that all five base stations produced interference above the
identified safety margin for an approach into O'Hare
Airport.6
In its publication, RTCA did not rule out the possibility of
"catastrophic failures leading to multiple fatalities, in the
absence of appropriate mitigations" due to the identified risk
of 5G interference to low-level aviation.7
The record-breaking 5G auction
As a result of the October 2020 RTCA report, multiple trade
groups such as Aerospace Industries Association, Air Line Pilots
Association, the National Business Aviation Association, and many
others, requested that the FCC consider mitigation
efforts.8 In early December 2020, the aviation
industry voiced its concern about the FCC's decision to
reallocate a portion of the 3.7-4.2 GHz frequency band to make the
3.7-3.98 GHz portion available for 5G use. The reallocation to 5G
may introduce interference to radar altimeters operating around the
world in the 4.2-4.4 GHz band. For this reason, the aviation
industry made a request to suspend the FCC's auction for
spectrum licenses scheduled to begin on December 8, 2020.
In addition, there was a December 1, 2020 request by the Federal
Aviation Administration and the Department of Transportation to
pause the FCC's auction.9
Notwithstanding the testing and report circulated by the RTCA,
or the petitions by the industry, the first phase of the FCC's
5G Spectrum Auction concluded on January 15, 2021.10
This was the highest-grossing spectrum auction ever in the
United States for the private-sector purchase of spectrum licenses
in the C-band. Gross proceeds for the auction were above US $80.9
billion. The auction results will lead to the improvement of
services to wireless consumers. Some of the auction proceeds will
go to some satellite operators who currently operate within the
C-band, in order to move those operations into another portion of
the spectrum. This raises questions about those whose altimeters
operate near the C-band and could be prone to interference as
outlined in the RTCA study.
The FCC has dismissed the concern raised by the RTCA and
believes that 5G operations within the C-Band will not cause
problematic interference given the 200Mghz buffer between the
C-band compared to the band within which radar altimeters operate.
Further, the FCC has communicated it has concerns about the
RTCA's comprehensive study, citing overly stringent parameters
adopted by the RTCA in its testing, and that the RTCA did not
itemize its data in terms of altimeter brand or
model.11 However, it is unclear if the FCC has its
own information about what altimeter brand or model it has deemed
is better at preventing 5G interference.
Successfully preventing 5G interference in aviation
The advent of 5G technology will change the way our world
communicates. It will assist driving economic growth, and
represents an advancement that the aviation and aerospace sector
should embrace. Nonetheless, there is only one comprehensive study
so far, and there exists an apparent lack of communication between
the RTCA and the FCC about the identified risk to aviation
safety.
Therefore, how global aviation and telecommunication
advancements will proceed in parallel is uncertain. The
advancements could mean changes to 5G operations, or perhaps it
could mean changes to altimeter designs, in an effort to reduce or
eliminate any interference. Honeywell, a leader in radar
altimeters, is apparently testing in this
space.12 However, designing and replacing
altimeters in all aircrafts that are potentially impacted by 5G may
not be feasible, and it is not clear if the aviation industry alone
as it stands could bear such a cost.
In France, the concern over the 5G risk resulted in a slowdown
of 5G deployment as the issue is further assessed by the DGAC (the
French-equivalent to Transport Canada or the FAA). In the case of
the DGAC, measures may be added to create zoning protection around
airports to adapt to the introduction of 5G "as with each
technological evolution" that occurs.13 The
approach in France could also lend itself to procedures changing in
how one uses avionics. Alternatively, this approach could impact
when and how 5G is utilized around certain airports. On February 3,
2021, the UAE's General Civil Aviation Authority issued Safety
Alert 2021-03 to address "major operational risks" that
5G technology could have on the operation of radio altimeters and
wireless avionics intra-communications Radio.14
In Canada, discussions are occurring between Transport Canada
(TCCA) and the Innovation, Science and Economic Development branch
of the government about the liability concerns raised with 5G
implementation. TTCA's proposed approach is safety-focused, in
that frequency band selection should not be influenced by economic
reasons or harmonization with what the United States is
doing.15
Conclusion
The long-term impact of 5G on aviation is still unknown. Yet,
within the nascent stages of this identified risk, potential
lessons are available and within reach.
Wireless telecommunication and the aviation industry are both in
existence with the end-goal of bringing people together and,
therefore, a lack of connection between these two giant industries
on the 5G issue is the antithesis of what each represents. A
significant risk has been identified that could influence altimeter
usage. However, currently only one comprehensive study by the RTCA
exists, which was distributed in October of 2020.
Alongside this development, economic factors are driving
wireless decisions on a necessary fast track. A lack of
understanding and discussion in the early stages of two industries
colliding (aviation and wireless communication) could lead to
catastrophic failures. Alternatively, turning back to the roots of
connectivity and engaging in open and compromising dialogue could
also lead to technical ingenuity. The second path, although more
challenging at this stage, may be the best option to ensure
continued economic growth alongside the preservation of aviation
safety.
Footnotes
1 One example of an incorrect altimeter reading leading
to catastrophic losses is the tragic accident of the Boeing 736-800 Turkish Airlines
flight 1951 on February 25, 2009 near Schiphol Airport,
Amsterdam.
2 Radio Technical Commission for
Aeronautics
3 Assessment of C-Band Mobile Telecommunications
Interference Impact on Low Range Radar Altimeter
Operations. RTCA October 2020 Report
4 Ibid.
5 RTCA October 2020 Report, page 44, section
8.1.2.
6 RTCA October 2020 Report, page 77, section
10.2.1.
7 RTCA October 2020 Report, page 88, section
11.2.
8 Federal Communications Commission filing:
ID1207131706609
9 As 5G auction continues, Pentagon turns to safety
planning
10 First phase record breaking 5G spectrum auction
concludes.
11 The military is scrambling to understand the
aviation crash risk from a new 5G sale
12 Honeywell to test private 5G
network
13 Sécurité : la DGAC retarde le
déploiement de la 5G dans les
aéroports
14 Safety Alert 2021-03 - Requirements to mitigate 5G
interference operational risks
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