---
title: "GM1 101. Terrain — ANNEX I — Part-DEFINITIONS, ATM/ANS · Avioverse"
description: "GENERAL In practical terms, depending on the method of data collection used, terrain represents the continuous surface that exists at the bare Earth, the…"
url: "https://avioverse.aero/regulations/easa/atm-ans/part-definitions/general/gm1-101-terrain"
---

# GM1 101. Terrain

ANNEX I — Part-DEFINITIONS · Regulation (EU) 2017/373 · EAR revision 12 Mar 2025

GM Guidance material

## GM1 101. Terrain

GENERAL

In practical terms, depending on the method of data collection used, terrain represents the continuous surface that exists at the bare Earth, the top of the canopy or something in-between, also known as ‘first reflective surface’.

GM — Regulation (EU) 2017/373 · ED Decision 2017/001/R · ATM/ANS Easy Access Rules · EAR revision 12 Mar 2025

[All rules in General provisions](https://avioverse.aero/regulations/easa/atm-ans/part-definitions/general)

Consolidated from the EASA Easy Access Rules (revision 12 Mar 2025, extracted 13 Oct 2026) for convenience. Not the official publication — verify against the Official Journal of the European Union and the EASA publications before operational use.