An unstart is a specific phenomenon where supersonic flow of air into the engine gets disrupted. It's very different from a compressor stall where the airflow

An unstart is a specific phenomenon where supersonic flow of air into the engine gets disrupted. It's very different from a compressor stall where the airflow _inside_ the engine is disrupted. Wikipedia has a pretty decent explanation: https://en.wikipedia.org/wiki/Unstart https://en.wikipedia.org/wiki/Unstart