Radio Regulations
Source: the Radio Regulations published by the International Telecommunication Union (ITU).
1.9
WRC-27 · Agenda item 1.9
to consider appropriate regulatory actions to update Appendix 26 to the Radio Regulations in support of aeronautical mobile (OR) high frequency modernization, in accordance with Resolution 411 (WRC-23)
At a glance Beta
What's being studied — points to watch
Wideband next to narrowband
Fitting wider digital emissions (aggregated beyond 3 kHz channels) alongside existing AM(OR)S systems and other primary services in the same or adjacent bands (Res. 411).
Appendix 26, allotments untouched
Any modification keeps the existing area allotments unchanged, and current narrowband use must be neither impacted nor precluded (Res. 411); Article 5 is not changed.
Transition from voice
Coexistence of legacy narrowband voice and new wideband digital during a long migration.
Propagation-driven sharing
HF coverage varies with time of day and solar activity, so sharing conditions must hold across changing propagation.
Preparation timeline
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Dec 2023 WRC-23 agenda adoptedDec 2023 WRC-23 agenda adopted
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Dec 2023 CPM 27-1 studies allocatedDec 2023 CPM 27-1 studies allocated
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ITU-R studies 2026ITU-R studies 2026
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ITU-R studies 2027ITU-R studies 2027
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5–15 Apr 2027 CPM 27-2 final report5–15 Apr 2027 CPM 27-2 final report
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RTO Prep meetings 2027RTO Prep meetings 2027
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11–15 Oct 2027 RA-2711–15 Oct 2027 RA-27
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18 Oct–12 Nov 2027 WRC-2718 Oct–12 Nov 2027 WRC-27
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Dec 2023 WRC-23 agenda adopted
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Dec 2023 CPM 27-1 studies allocated
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ITU-R studies 2026
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ITU-R studies 2027
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5–15 Apr 2027 CPM 27-2 final report
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RTO Prep meetings 2027
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11–15 Oct 2027 RA-27
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18 Oct–12 Nov 2027 WRC-27
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Source: ITU Radio Regulations, editions of 2008, 2012, 2016, 2020 and 2024. The English, French and Spanish texts are each taken from the official edition in that language, not translated from one another. Sources and citation.