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ACP-WGF22/IP-xx
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International Civil Aviation Organization
INFORMATION PAPER / ACP-WGF22/IP-12
13 April 2010

AERONAUTICAL COMMUNICATIONS PANEL (ACP)

22nd MEETING OF WORKING GROUP F

Mexico city, 23April – 30 April 2010

Agenda Item 5: / Interference from non-aeronautical sources

Sky Terra /Inmarsat Spectrum concerns

(Presented by Claude Pichavant)

SUMMARY
This paper copies a paper provided by the FCC about Sky Terra subsidiary LLC . Used sources are RTCA, Inmarsat, & Sky Terra
ACTION
To note the paper and take the information into consideration when preparing any working papers with respect to WRC-12 Agenda Item 1.7 Resolution 222.

1.INTRODUCTION

1.1General Information about SkyTerra

SkyTerra Communications, is a leadingUnited States provider of Services under Mobile Satellite Service allocations (“MSS”)

SkyTerra operates a 2 Geostationary mobile satellite network inNorth America that provides voice and data applications to more than 300,000 Units.

SkyTerra is nearing completion of a next-generation system that willcombine two of the most powerful commercial satellites ever built with anAncillary Terrestrial Component (“ATC” or “ATCt”)

The next-generation system will be capable of providing nationwide wireless voice and broadband services using the L-band satellite frequencies.

According to Sky Terra, there are two interference scenarios under consideration (ATC Interference to Aero Terminals) :

•Aggregate uplink interference caused by a collection of ground-based ATC sources of interference to an in-flight AES: “Aero Model”

•Interference caused by a single ground-based ATC base station near an AES on a plane on the ground, addressing overload and out-of-band interference issues: ”Proximity Model”

Over the past two years, Inmarsat and SkyTerra have been workingto find a way to resolve the L Band issues so as to ensure USconsumers will fully enjoy broadband offerings in this band.

A comprehensive Co-Co-operation agreement was signed and relevant Highlights of the agreement include:

• Long-term agreement on coordination of all the parties’ current and nextgeneration satellites covering North America, increasing spectrumefficiency and protecting both MSS and ATCt operations from harmfulinterference.

• Increased technical flexibility and system enhancements that will enablegreater broadband ATCt usage and operations, while protecting nextgenerationMSS capability of both Inmarsat and SkyTerra.

1.2Background

According to the last FCC adoption, refer to enclosed Attachment 1 (FCC DA 10-354):

Quote ““The Communications Act does not require the Commission to rule on each application in a way that minimizes interference to each and every end user. If it did, we would be obliged to denySkyTerra’s contested waiver requests. Its ATC base stations, operating as proposed in its application,will cause interference over wider areas than they would if operated in strict compliance with the ATC

rules. The Communications Act, however, does require that the Commission consider the overall publicinterest, even though that consideration may negatively impact one or more private interests. In carryingout this mandate, the Commission retains discretion to waive a rule designed to limit interference if it

finds that granting such relief will better serve the public interest than insisting on strict compliance. Aswe discuss more fully below, we conclude that the public interest would on balance best be served bygrant of SkyTerra’s request.””Unquote

2.discussion

This decision leads to Airframers(and Airlines)concerns.

Currently most of long range aircraft use SATCOM system for oceanic routes to be compliant with Airworthiness requirements; SATCOM is used for FANS (Datalink), ATC voice (compliance with AC20-150 FAA recommendations) and passenger connectivity. Note that MMEL (Master Minimum Equipment list) was revisited to take advantages of SATCOM operation and thatone HF system can be removed from the list when SATCOM is installed on board.

It must noted that a lot of short range aircraft use alsoSATCOM on non oceanic airspace for Datalink and SBB (VoIP/Internet) even if in VHF coverage.

For existing equipped aircraft, the RTCA SC-222 committee needs to assess the impact to airlines who do not want to upgrade their Inmarsat SATCOM terminals. It will be important to characterize the interferences in order to inform operators of the pending actions required to maintain existing services (FANS..).When SkyTerra ATCt interference will occur, it shall be necessary to inform users that Inmarsat aeronautical service is no more possible or limited.

For new manufactured aircraft, the RTCA SC-222 committee will assess also the need to update the following RTCA documents:DO-210D, DO-262A NGSS MOPS, DO-270A NGSS MASPS as well as the associated ARINC characteristics (ARINC 741, 761, 781..). If changes are required, the Special Committee will identify the scope of such changes and recommended locations within the relevant documents.

There is a high risk that changing the DLNA (Diplexer/Low Noise Amplifier) and changing or updating the SDU (Satellite Data Unit) may not be a sufficient list of changes required to Inmarsat terminals to prevent interference from SkyTerra.

In any case certification scope/demonstration will need probablyalso to be revisited (expected FANS performances..)

3.ACTION BY THE MEETING

3.1The ACP WGF is invited to note the information provided and, where appropriate, use the information in preparing contributions to regional and global meetings with respect to WRC-12 Agenda Item 1.7 Resolution 222.

Attachment 1