---
title: "GM1 HPT-DSN.E.420 Take-off climb surface — Certification Specifications and Guidance Material for Heliport Design (CS-HPT-DSN) — Issue 1, Aerodromes · Avioverse"
description: "Helicopter take-off performance is reduced in a curve, so a straight portion along the take-off climb surface prior to the start of the curve allows for…"
url: "https://avioverse.aero/regulations/easa/aerodromes/cs-hpt-dsn/chapter-e-obstacle-limitation-surfaces-and/gm1-hpt-dsn-e-420"
---

# GM1 HPT-DSN.E.420 Take-off climb surface

Certification Specifications and Guidance Material for Heliport Design (CS-HPT-DSN) — Issue 1 · Regulation (EU) No 139/2014 · EAR revision 13 Mar 2026

GM Guidance material

## GM1 HPT-DSN.E.420 Take-off climb surface

(a) Helicopter take-off performance is reduced in a curve, so a straight portion along the take-off climb surface prior to the start of the curve allows for acceleration.

(b) For heliports intended to be used by helicopters operated in performance class 2 and 3, it is an operational requirement for departure paths to be selected so as to permit safe forced landings or one-engine-inoperative landings such that injury to persons on the ground or damage to property are minimised. The most critical helicopter type for which the [heliport](https://avioverse.aero/glossary/easa/heliport) is intended and the ambient conditions may be factors in determining the suitability of such areas.

(c) The approach and take-off surfaces should be offset from each other ideally by an angle of not less than 135 degrees.

GM · GM1 HPT-DSN.E.420 — Regulation (EU) No 139/2014 · ED Decision 2019/012/R · Aerodromes Easy Access Rules · EAR revision 13 Mar 2026

[All rules in CHAPTER E — OBSTACLE LIMITATION SURFACES AND REQUIREMENTS](https://avioverse.aero/regulations/easa/aerodromes/cs-hpt-dsn/chapter-e-obstacle-limitation-surfaces-and)

Consolidated from the EASA Easy Access Rules (revision 13 Mar 2026, 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.