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February 21, 2020

FILED VIA ECFS

Marlene H. Dortch

Secretary

Federal Communications Commission

445 12th Street, SW

Washington, DC 20554

Re: Notice of Ex Parte Meetings, GN Docket No. 18-122

Dear Ms. Dortch,

On February 19, 2020, Max Fenkell of the Aerospace Industries Association; Andrew

Roy of Aviation Spectrum Resources, Inc. (“ASRI”); Edward A. Yorkgitis, Jr. of Kelley Drye &

Warren, LLP, counsel for ASRI; Ed Hahn of Air Line Pilots Association, International

(“ALPA”); Robert Ireland of Airlines for America; and Bobby Sturgell of Collins Aerospace;

Harold Summers of Helicopter Association International; Capt. David Sambrano and Max

Slutsky, United Airlines, and the following participants by telephone, David Redman and Fred

Fisher of the Aerospace Vehicle Systems Institute (“AVSI”); Bryan Lesko of ALPA; James

Dickens of Bristow Group Global Communications; Sai Kalyanaraman and Megan Rosia of

Collins Aerospace; Aubrey Stevens of Delta Airlines; Chris Naugle of FedEx; Clay Barber and

Eddie Straub of Garmin International; Seth Frick of Honeywell; Noppadol Pringvanich of the

International Air Transport Association (“IATA”); and Neal Young of Southwest Airlines

(collectively, the “Aerospace/Aviation Representatives”) met separately with Aaron Goldberger,

Wireless Advisor to Chairman Ajit Pai; Will Adams, Wireless Advisor to Commissioner

Brendan Carr; and William Davenport, Wireless Advisor to Commissioner Geoffrey Starks.1

The PowerPoint presentation used during the meetings is appended hereto.

The Aerospace/Aviation Representatives emphasized that radio altimeter systems are

critical mandatory safety equipment on commercial passenger aircraft, cargo carrier aircraft, and

helicopters, as well as widely deployed on general aviation aircraft. Further, radio altimeters will

1 Mr. Sturgell participated only in the meeting with Mr. Adams.

KELLEY DRYE & WARREN LLP

Ms. Marlene H. Dortch

February 21, 2020

Page Two

be used increasingly on unmanned aircraft vehicles, commonly referred to as UAVs or drones.

The Aerospace/Aviation Representatives provided a high-level overview that ongoing testing

and analysis that has been submitted into the record by the aerospace and aviation industries

confirming that the performance of radio altimeter radar systems operating in the 4200-4400

MHz band would be subject to potential serious degradation from deployments of flexible-use

systems in the 3700-3980 MHz band under consideration in the above-referenced docket unless

appropriate action is taken to protect such devices.

The Aerospace/Aviation Representatives explained the reality that the Draft R&O in this

proceeding,2 while it acknowledges that radio altimeters “must operate without harmful

interference,”3 would not, if adopted as is, offer appropriate protection of the embedded base of

tens of thousands of radio altimeters. They explained that the Draft R&O’s statement that

“significant protection” of radio altimeters and commitment that the Commission will “monitor

the results of . . . studies as they are provided” and “take appropriate action, if necessary, to

protect [radio altimeters],”4 does not go far enough because the data in the record now show that

there is a real risk of potential interference to radio altimeters in permissible, real-world aviation

configurations. The Aerospace/Aviation Representatives noted that the flying public requires

more assurance than significant protection – instead the integrity of radio altimeters must be

assured to 10-9 reliability, i.e., performance measured to “nine nines.”5

The aerospace and aviation industries recognize the desire of the Commission to provide

potential auction participants in the to-be-cleared 3700-3980 MHz band with information before

the anticipated December 2020 auction regarding any mitigation measures under which flexible-

use licensed systems must operate in that band. Accordingly, to address this situation, and

protect aviation safety while allowing the auction to proceed for all 280 megahertz as planned,

firmness and speed in implementing a process to address interference prevention, detection,

mitigation, and enforcement will be key.

The Aerospace/Aviation Representatives, therefore, proposed the following as

appropriate and necessary modifications in the final Report and Order to protect radio altimeters:

2 See Expanding Flexible Use of the 3.7 to 4.2 GHz Band, GN Docket No. 18-122, Draft

Report and Order and Order of Proposed Modification, FCC-CIRC2002-01 (Feb. 7, 2020)

(“Draft R&O”)

3 Id. ¶ 347.

4 Id. ¶ 351.

5 See id. (tentatively concluding that “[t]he technical rules on power and emission limits

[the Commission would] set for the 3.7 GHz Service and the spectral separation of 220

megahertz offers significant protection of services in the 4.2-4.4 GHz band” (emphasis added)).

KELLEY DRYE & WARREN LLP

Ms. Marlene H. Dortch

February 21, 2020

Page Three

The Commission’s adopted Report and Order must make clear not only that

Federal Aviation Administration (“FAA”)-certified radio altimeters must operate

without harmful interference, but that flexible-use licensees in the 3700-3980 MHz

band (1) will be responsible for preventing harmful interference to radio altimeters

and (2) resolve any interference that does occur.

The adopted Report and Order should provide that the Commission, through the

Office of Engineering and technology and the Wireless Telecommunications

Bureau, will immediately convene a multi-stakeholder group to provide a forum for

the aerospace, aviation, and commercial wireless industries to work expeditiously

and cooperatively to advance the assessment of the potential for interference – by

both flexible mobile base stations and handsets – to the embedded base of tens of

thousands of FAA-certified radio altimeters; develop efficient, technical solutions;

and propose regulatory measures to implement such solutions.6 Among other

things, the stakeholders should conduct an integrity impact assessment to

determine the interference tolerance level at which the required system integrity of

altimeters is maintained in the presence of the range of prospective deployment of

flexible-use operations. The FAA and National Telecommunications and

Information Administration should be invited, as appropriate, to participate

throughout the stakeholder group process.

The Aerospace/Aviation Representatives emphasized that taking these actions over the

next approximately four months would allow a second order to be issued by the Commission to

better address the concerns raised by the aviation industry and protect radio altimeters, while

giving prospective bidders in the 3700-3980 MHz band time to take into account the results of

this multi-stakeholder effort and resulting Commission order when formulating their bids. The

aerospace and aviation industry respectfully suggests that this proactive set of time-bounded

actions is a far more sound approach from the public interest perspective than simply, as the

Draft R&O suggests the Commission may be considering, monitoring aviation’s studies and later

starting a process to take appropriate action, with a risk of imposing additional requirements after

the auction ends.

6 The proposal for such a forum is modeled on the multi-stakeholder group that the Draft

R&O envisions would be convened to address flexible-use and C-Band satellite service

coexistence and “develop a proposed framework for interference prevention, detection,

mitigation, and enforcement in the 3.7-4.2 GHz band.” See Draft R&O at ¶ 296. There can be

no doubt that if this type of forum is a good idea to help protect video content distribution and

other earth station-supported services, it is equally the right approach to ensure the safety of the

flying public.

KELLEY DRYE & WARREN LLP

Ms. Marlene H. Dortch

February 21, 2020

Page Four

This notice is being filed as required by Section 1.1206 of the Commission’s rules for

inclusion in the record for Docket No. 18-122.7

Respectfully submitted,

Edward A. Yorkgitis, Jr.

Counsel for Aviation Spectrum Resources,

Inc.

Attachment

cc (via email): Aaron Goldberger

Will Adams

William Davenport

7 47 C.F.R. § 1.1206.

Flexible Use Operations in 3.7-4.2 GHz:Ensuring Aviation Safety and Protecting Radio Altimeters in the 4.2-4.4 GHz Band

GN Docket No. 18-122

Domestic and International Aviation/Aerospace Organizations

Meeting with the office of Chairman PaiMeeting with the Office of Commissioner CarrMeeting with the Office of Commissioner Starks

February 19, 2020

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Introduction

• The aviation industry recognizes the desire to provide potential bidders information before the auction regarding any technical restrictions under which flexible use licensed systems must operate in the 3700-3980 MHz.

• The aviation industry appreciates that Chairman Pai intends that “any actions the Commission takes to repurpose the C-band should not interrupt existing services, including the use of altimeters by helicopters and airplanes in the 4.2-4.4 GHz band.” Jan. 24, 2020, reply to Rep. DeFazio

• Similarly, the draft R&O acknowledges that radio altimeters “must operate without harmful interference” and indicates that the Commission will “monitor the results of . . . studies as they are provided” and “take appropriate action, if necessary, to protect [radio altimeters].” (Draft R&O, ¶¶347, 351)

• The current record, recently updated and properly interpreted, indicates that harmful interference to radio altimeters will likely result under permissible aviation configurations, necessitating appropriate action.

2

Radio Altimeter Use by Aviation Is Extensive in All Airspace

• Used by tens of thousands of aircraft daily across the USA at all altitudes• Large commercial aircraft (both domestic and international)• Private aircraft• Helicopters• Drones/UAVs

• System supports a number of safety functions that modern aviation deems essential for safety• Terrain Awareness and Warning System (TAWS)• Autoland function• Flight by instruments, no visual available• Auto deployment of systems required at low altitudes

• Radio altimeters are all certified by the FAA as aviation safety equipment

3

The Draft R&O Does Not Have a Foundation to Assure Aviation Safety

• The AVSI data and conclusions indicate more must be done to protect aviation systems• Empirical data supported by all major radio altimeter manufacturers• Developed by aerospace industry to support international standards at ICAO• AVSI results, including refinement and update, demonstrate that in permissible aviation configurations radio

altimeters in use today will be compromised• Interference case study shared with OET/WTB February 14 further reveals problem in a basic low-altitude

scenario, especially for general aviation and helicopters

• No alternate studies have been submitted into the record other than T-Mobile/Alion statements in a high-level presentation• Comments that aviation safety issue is ‘unlikely’ without supporting data not a method to determine aviation

safety• T-Mobile/Alion fail to understand need to ensure aviation safety in all permissible conditions

• Taken as a whole, the record substantiates the need for further action now to ensure aviation safety by protecting radio altimeters from harmful interference

The Integrity of Radio Altimeters Must Be Assured to 10-9 Reliability(i.e., “Nine Nines”)

4

The T-Mobile/Alion Critique of the AVSI Data Misses the Mark and Provides an Insufficient Basis for Decision

• The existing in-band interference margin was developed by AVSI on a real-world worst-case operational example• Has been discussed and validated at ITU-R, ICAO, and international aviation standards bodies

• The interference source AVSI used is spectrally representative of the 5G waveforms• Radio altimeter receivers do not distinguish between different types of OFDM signals; all are

broadband noise sources for the radio altimeter

• Out-of-band signals from simulated interference not a driving factor in the final AVSI results• T-Mobile misinterpreted spectrum analyzer noise floor and results do not support such a

conclusion

The T-Mobile input is insufficient to support the recommended inaction in the Draft R&O

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Conclusion and Path to a Solution• The adopted R&O must make clear not only that FAA certified radio altimeters are protected,

but that flexible use licensees in the 3700-3980 MHz will have the responsibility to prevent harmful interference to radio altimeters and resolve any interference that does occur

• The Commission, through OET and WTB, should convene a multi-stakeholder group to provide a forum for industry to work expeditiously and cooperatively (over the next four months) to advance the assessment of the potential for interference – from base stations and handsets, including those in the air cabin – to the embedded base of FAA certified radio altimeters, develop efficient, technical solutions, and propose regulatory measures to implement such solutions

• The FAA and NTIA should be invited to participate throughout the process to ensure system integrity is maintained to the necessary requirements

• Such a forum is modeled on the group that the Draft R&O envision will be convened to address flexible use and C-Band satellite service compatibility (Draft R&O, ¶296)

• T-Mobile called for a multi-stakeholder assessment in its opening comments in this proceeding

Given the reality of the embedded base of radio altimeters, the safety of the flying public requires further attention to this matter on an expedited basis

6