Which inputs influence takeoff distance to clear an obstacle?

• A. Weight, altitude, temperature, wind, runway slope, and obstacle height and geometry
• B. Only weight and altitude
• C. Only temperature and wind
• D. Only runway slope and obstacle geometry

Answer: (A)

The main idea is that taking off to clear an obstacle is about how the airplane performs given its weight, the air density it’s flying in, wind effects, the slope of the runway, and what the obstacle requires you to clear. Heavier weight raises the speed you must reach to generate enough lift, so the takeoff distance grows. Lower air density from higher altitude or higher temperature reduces engine thrust and wing lift, making the takeoff longer. Wind changes how fast you gain effective airspeed versus ground distance: a headwind shortens the ground roll because you achieve the needed airspeed sooner, while a tailwind lengthens it. Runway slope adds a gravity component during roll and rotation: an uphill slope increases the distance you must cover, whereas a downhill slope can reduce it. Finally, the obstacle height and geometry dictate the climb gradient you must achieve after liftoff to clear it, which directly determines how much distance is needed before you can safely pass above the obstacle.

So all of these inputs—weight, altitude, temperature, wind, runway slope, and obstacle characteristics—shape the required takeoff distance to clear an obstacle.