Definition
A condition in a turbine engine compressor in which airflow momentarily stops moving rearward through the engine and instead surges forward, opposite to the normal direction of flow. It is the most severe form of compressor stall and is typically accompanied by a loud bang, vibration, and a sudden loss of thrust.
Plain English
The air inside the engine, which should be flowing from front to back, suddenly slams backwards and tries to come out the front. It usually makes a loud bang and the engine loses power.
Context Anchor
Seen in turbine engine operating discussions, especially when learning the symptoms and risks of compressor stalls.
Why Pilots Care
Flow reversal can produce engine surge, rapid loss of thrust, and possible compressor damage if power and airspeed are not adjusted immediately.
Grounding Statement
Picture air entering the front of the engine, then a pressure upset inside the engine briefly shoves some of that air back toward the front.
Intuition Check
Flow reversal does not mean the aircraft reverses direction or that normal reverse thrust is being used. It means the airflow inside the engine is briefly moving opposite its normal direction.
Example Sentence 1
The crew heard a loud bang and felt a sharp yaw as the compressor experienced a flow reversal during the climb.
Example Sentence 2
Increasing airspeed and reducing throttle helped restore normal airflow and ended the flow reversal.