Definition
The point on a body in a moving airflow where the local airflow velocity is zero. Air striking the body splits at this point and flows around either side of it. Because the airflow is brought to rest, static pressure at the stagnation point is at its highest value for that body in that flow.
Plain English
The exact spot on a wing, propeller blade, or other surface where the oncoming air comes to a complete stop and then divides — some going over the top, some going under the bottom.
Context Anchor
Seen in aerodynamics and airframe discussions about airflow over wings, engine inlets, probes, and other surfaces facing the airflow.
Derivation
From Latin 'stagnare' meaning 'to stand still' or 'be motionless.' At the stagnation point the air is, quite literally, standing still relative to the surface — which is exactly what the word describes.
Why Pilots Care
Stagnation points are where ice tends to form first on a leading edge, and where pitot tubes are designed to sense the highest pressure in the airflow. Knowing where the stagnation point sits helps explain how airspeed indicators work and why ice protection focuses on leading edges.
Analogy
Think of water from a hose hitting a wall. Right where the stream hits, the water briefly stops before spreading sideways; that hit spot is like a stagnation point.
Grounding Statement
Picture air flowing toward a wing's leading edge: there is one line along the leading edge where the air can't go up or down — it just stops. That line is made up of stagnation points.
Intuition Check
Stagnation does not mean all the air around the airplane has stopped. It means one exact spot where the airflow slows to zero before moving around the surface.
Example Sentence 1
The pitot tube is positioned so that its opening sits at the stagnation point of the oncoming airflow, allowing it to sense full ram pressure.
Example Sentence 2
Ice tends to accumulate first at the stagnation point because that is where the airflow slows and deposits moisture.