Definition
The angle, measured from the horizontal, at which a projectile or aircraft leaves its point of origin and begins its trajectory or climb path.
Plain English
The upward angle at which something takes off or leaves the ground, measured against level ground.
Context Anchor
Seen in takeoff performance, obstacle clearance, and climb discussions.
Derivation
From Latin 'departire,' meaning 'to divide' or 'to go away from.' The angle of departure is literally the angle at which something departs from a reference point — usually the ground or a launch surface.
Why Pilots Care
A steeper angle of departure can clear obstacles after takeoff, but it also reduces forward speed and can compromise climb performance if pushed too far. Knowing the right angle for the conditions matters for safe obstacle clearance.
Analogy
It is like looking at the steepness of a road as it rises away from flat ground. A steeper road makes a larger angle with the flat ground.
Grounding Statement
Picture the aircraft from the side: the angle of departure is the upward slant of its path after it leaves the runway.
Intuition Check
Departure does not mean an ATC departure route here. It means the aircraft’s upward path as it leaves the ground after takeoff.
Example Sentence 1
On a short field with trees off the end of the runway, the pilot needed a steep angle of departure to clear the obstacles safely.
Example Sentence 2
A headwind increased the angle of departure and allowed a shorter ground roll before liftoff.