According to obstacle limitation surfaces for an instrument runway, the approach surface next to the runway end rises outward at which slope?
Civil Engineering
Airport Engineering
Difficulty: Medium
Choose an option
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A1 in 20
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B1 in 30
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C1 in 40
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D1 in 50
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ENone of the above
Answer
Correct Answer: 1 in 40
Explanation
Introduction / Context:Obstacle Limitation Surfaces (OLS) define protected airspace around aerodromes. For instrument runways, the approach surface begins at the runway end and rises outward at a prescribed slope to ensure obstacle clearance for instrument approaches.
Given Data / Assumptions:
- Instrument (non-precision) runway typical approach surface slope is commonly taken as 1:40.
- Precision approaches may include inner and transitional surfaces with differing slopes; however, the standard non-precision approach surface slope is the focus.
Concept / Approach:By specifying a vertical rise per unit horizontal distance, the OLS controls permissible obstacle heights. The 1:40 slope is a widely referenced value for instrument runways without precision categories.
Step-by-Step Solution:
Evaluate common OLS values: visual runway ~1:20, non-precision instrument ~1:40, precision inner portions may be flatter with special segments.Thus, for a general “instrument runway” context, select 1 in 40.Verification / Alternative check:
Cross-check aerodrome design manuals or national adaptations of ICAO Annex 14 showing approach surface slopes by runway classification.Why Other Options Are Wrong:
1:20 and 1:30 are steeper, typical of visual/runway types; 1:50 is flatter and often associated with precision inner/outer rules, not the general non-precision case in this phrasing.Common Pitfalls:
Confusing visual, non-precision, and precision categories; mixing inner approach vs overall approach surfaces.Final Answer:
1 in 40