Helicopter Sizes

Understanding Helicopter Sizes for Safe Landing Site Design

On Helipaddy, we avoid type-certification complexity and instead use a single practical metric:

Largest aircraft dimension (D) – the maximum overall diameter of the helicopter, in metres.

This value directly drives the three concentric safety circles used in Helipaddy site assessments:

• Circle 1 (Touchdown area) ≈ 0.85 × D
• Circle 2 (Operational area) = D
• Circle 3 (Clear zone) = 2 × D

---

Light Single-Engine Helicopters (≈12–13 m)

These are the most common private and utility helicopters seen at rural and residential sites.

• Robinson R44 — D 12.1 m

• Airbus H135 — D 12.2 m

• Bell 407 — D 12.6 m

• Airbus H125 — D 12.9 m

Key point:

Even “small” helicopters still require a 25 m clear diameter once safety margins are applied.

---

Larger Light / Entry-Level Twin Helicopters (≈13–14 m)

These aircraft look only slightly larger than those above but materially increase clearance needs.

• Robinson R66 — D 13.3 m

• Airbus H145 — D 13.6 m

Design implication:

Selecting 13.6 m instead of 12.1 m increases the required clear zone by over 3 metres radius.

---

Medium Twin Helicopters (≈15–17 m)

These aircraft are common for corporate, medical, offshore, and charter operations.

• Leonardo AW169 — D 15.7 m

• Sikorsky S-76 — D 16.0 m

• Leonardo AW139 — D 16.6 m

Reality check:

A site suitable for an R44 is not remotely suitable for an AW139 without major clearance.

---

Large Helicopters (≈20 m)

• Leonardo AW189 — D 19.5 m

These aircraft require nearly 40 m of unobstructed diameter. They are rarely compatible with private sites unless purpose-built.

---

Practical Guidance for Site Owners

• Do not size for the helicopter you expect — size for the helicopter you might get.
• A visiting charter, medical diversion, or upgraded aircraft can easily exceed expectations.
• Choosing the next size up costs nothing on paper and avoids future rejections.
• Pilots will not “squeeze in” — they will simply not land.

Helipaddy’s Largest Dimension D selector exists to make this decision simple, conservative, and defensible.

Helipaddy Landing Site Wizards

If you are wondering if your location can be used for helicopters, you may find our Landing Site Check wizard helpful.

If you are considering building a helipad and want to specify it, try our Build A Helipad wizard.