Airport engineering (ICAO): what elevation correction rate is recommended for basic runway length with respect to height above mean sea level (MSL)?
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A1% for every 100 m of elevation above MSL
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B7% for every 300 m of elevation above MSL
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C2% for every 500 m of elevation above MSL
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D2% for every 300 m of elevation above MSL
Answer
Correct Answer: 7% for every 300 m of elevation above MSL
Explanation
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