What is the maximum slope angle, in degrees, on which helicopters can land?

• A. 12
• B. 18
• C. 20
• D. 15

Answer: (D)

When a helicopter lands on a slope, the crucial idea is stability: the center of gravity must stay within the footprint formed by the landing gear as the aircraft tilts with the ground. The rotor can provide lift, but if the slope is too steep, the weight’s vertical projection moves outside that base, making tipping or loss of stable contact likely. That’s why there’s a practical maximum slope angle for landing.

Around 15 degrees represents the typical upper limit for many helicopters in standard operating conditions, balancing enough incline tolerance with safety margins. A smaller value, like 12 degrees, is safer but not the maximum. Larger angles, such as 18 or 20 degrees, push beyond what many helicopters are rated to handle safely and increase tipping risk. So 15 degrees is the best answer.