Airport engineering (ICAO): what elevation correction rate is recommended for basic runway length with respect to height above mean sea level (MSL)?

Introduction / Context:Runway length corrections account for reduced air density at higher elevations, which impairs aircraft take-off performance. ICAO-recommended adjustments scale the basic runway length with altitude above MSL.

Given Data / Assumptions:

• Correction is expressed as a percentage increase per specified elevation increment.
• Standard ICAO teaching reference uses 7% per 300 m elevation.

Concept / Approach:As elevation increases, density decreases, requiring greater ground roll and therefore longer runway. The rule-of-thumb correction percentage is applied additively to the basic runway length determined under standard conditions.

Step-by-Step Solution:Identify ICAO correction: +7% per 300 m.Apply proportionally to the basic runway length as needed.

Verification / Alternative check:Airport design manuals and exam standards consistently list 7% per 300 m as the elevation correction.

Why Other Options Are Wrong:

• Other percentages or increments do not match the ICAO recommendation used in standard problems.

Common Pitfalls:

• Confusing elevation correction with temperature or gradient corrections, which are separate.

Final Answer:7% for every 300 m of elevation above MSL