Per 14 CFR Part 25 certification standards, the net takeoff flight path (gross flight path reduced by the required gradient decrements) must clear all obstacles within the obstacle accountability area by what minimum margin?
- A35 feet vertically, or 90 feet horizontally while still within the boundaries of the airport
- B50 feet vertically only, with no horizontal clearance credit permitted
- C35 feet vertically, or 200 feet horizontally beyond the airport boundary
- D15 feet vertically, or 50 feet horizontally within the airport boundary
Show answer & explanationAnswer & explanation
Correct answer: A. 35 feet vertically, or 90 feet horizontally while still within the boundaries of the airport
Part 25 requires the net takeoff flight path to clear all obstacles by at least 35 feet vertically, or by 90 feet horizontally within the boundaries of the airport and 50 feet plus 0.125 times the horizontal distance traveled beyond the airport boundary (up to 300 feet). The 35-foot vertical / 90-foot horizontal-within-airport figures are the foundational clearance standard.
Why the other options are wrong
- B. Horizontal clearance credit is permitted under Part 25, not disallowed.
- C. 200 feet horizontal beyond the boundary is not correct; horizontal clearance varies with distance traveled.
- D. 15 feet and 50 feet are not the certification clearance values.
Net Takeoff Flight Path Obstacle Clearance
The net flight path (gross path reduced by required gradient decrements) must clear obstacles by at least 35 feet vertically, or 90 feet horizontally while within airport boundaries.
- Net flight path = gross flight path minus gradient decrement (0.8% for 2-engine).
- Vertical clearance minimum: 35 feet.
- Horizontal clearance within airport boundary: 90 feet.
- Beyond the airport boundary, horizontal clearance increases with distance traveled, up to 300 feet.
Memory trick: Thirty-five feet up, or ninety feet over — clear the obstacle, stay clever.