---
title: "Mode (SSR) — EASA Definition · Avioverse"
description: "Article 2, Regulation (EU) No 923/2012: ‘mode (SSR)’ means the conventional identifier related to specific functions of the interrogation signals…"
url: "https://avioverse.aero/glossary/easa/mode"
---

# mode (SSR)

EASA defines “mode (SSR)” in one regulation. The wording below is reproduced verbatim from the EASA Easy Access Rules, with a link to the paragraph it comes from.

> ‘mode (SSR)’ means the conventional identifier related to specific functions of the interrogation signals transmitted by an SSR interrogator. There are four modes specified in ICAO Annex 10: A, C, S and intermode;
>
> 95a. ‘model aircraft’ means an unmanned aircraft, other than toy aircraft, having an operating mass not exceeding limits prescribed by the competent authority, that is capable of sustained flight in the atmosphere and that is used exclusively for display or recreational activities;
>
> 95b. ‘mountainous area’ means an area of changing terrain profile where the changes of terrain elevation exceed 900 m (3 000 ft) within a distance of 18,5 km (10,0 NM);

Article 2 · Standardised European Rules of the Air (SERA) · Regulation (EU) No 923/2012 · Easy Access Rules, 26 Aug 2025 revision · [Read Article 2](https://avioverse.aero/regulations/easa/sera/cover-regulation/powers-and-recital#article-2)

## Defined in the same article

- [accuracy](https://avioverse.aero/glossary/easa/accuracy)
- [advisory airspace](https://avioverse.aero/glossary/easa/advisory-airspace)
- [advisory route](https://avioverse.aero/glossary/easa/advisory-route)
- [aerial work](https://avioverse.aero/glossary/easa/aerial-work)
- [aerobatic flight](https://avioverse.aero/glossary/easa/aerobatic-flight)
- [aerodrome](https://avioverse.aero/glossary/easa/aerodrome)
- [aerodrome control service](https://avioverse.aero/glossary/easa/aerodrome-control-service)
- [aerodrome control tower](https://avioverse.aero/glossary/easa/aerodrome-control-tower)