Definition
A radar return pattern showing many small, closely grouped echoes that move together, typically caused by a flock of birds, a swarm of insects, or scattered light precipitation. The name describes how the returns look on the radar display — clustered dots drifting as a group, similar to a school of fish on a sonar screen.
Plain English
A bunch of small blips on a radar screen that move together as a group, usually from birds, bugs, or light rain rather than aircraft.
Context Anchor
Seen in aerial fish-spotting, coastal flying, maritime patrol, and other low-level operations over water.
Derivation
A descriptive nickname borrowed from marine biology. Just as fish swim in tight, coordinated groups, these radar returns appear as a cluster of small dots moving together across the screen.
Why Pilots Care
Knowing that a cluster of small radar returns is likely a bird flock — not traffic or weather — helps pilots and controllers correctly interpret what they are seeing and avoid bird strike hazards in the area.
Grounding Statement
From the cockpit, a school of fish may appear as a patch of water that looks different from the surrounding surface because many fish are moving together below or near it.
Intuition Check
Do not read “school” as a training organization here. In this term, a school is a group of fish moving together.
Example Sentence 1
The controller advised the pilot that the small returns north of the field were likely schools of fish from a flock of migrating birds.
Example Sentence 2
From cruise altitude the scattered buoys looked like schools of fish on the surface.