Maximum runway slope approximately?

• A. +/- 1.0%
• B. +/- 2.0%
• C. +/- 3.0%
• D. +/- 4.0%

Answer: (B)

Runway slope is the vertical change along the length of the runway, expressed as a percent. That slope affects how aircraft accelerate for takeoff, how much distance is needed to stop after landing, and how climb performance is shaped after liftoff. For broad civil aviation use, keeping the slope within about plus or minus two percent provides a practical balance: it keeps performance changes within what pilots and flight manuals plan for, preserves usable runway length under various conditions, and is achievable in building and maintaining runways. If the slope were steeper, on uphill sections takeoff distances would increase and climb performance could suffer, while downhill sections would make braking and speed control more challenging, especially in wet or icy weather. Slopes of three or four percent would push many aircraft beyond their published performance envelopes. Hence, the commonly accepted maximum is around plus or minus two percent.