Definition
An aircraft flown in proximity to another aircraft, normally to observe its performance during training or testing.
Plain English
A second aircraft that flies alongside another one to watch it, usually during a test flight or training exercise.
Context Anchor
Seen in flight testing, training flights, and operations where one aircraft is assigned to observe another from nearby.
Derivation
From the everyday word 'chase,' meaning to follow or pursue. Here it does not mean catching something — it means flying along with another aircraft to observe it.
Why Pilots Care
Gives pilots on the ground or in the lead aircraft an outside view of maneuvers they cannot see themselves, improving safety during high-risk or experimental flying.
Intuition Check
Do not read chase as simply “trying to catch” another aircraft. In this FAA meaning, a chase aircraft is deliberately assigned to fly nearby and observe.
Example Sentence 1
A chase aircraft flew alongside the prototype to monitor its handling during the first test flight.
Example Sentence 2
Each student flew with a chase aircraft overhead for the first solo aerobatic sortie.