What happens if an aircraft engine stalls?

When an aircraft engine stalls, it typically indicates that the engine is not generating enough power to maintain normal operational parameters. This situation can occur due to various factors such as airflow disruption, fuel starvation, or mechanical issues. An engine stall leads to a significant decrease in thrust, which can affect the aircraft's ability to climb or maintain altitude.

Understanding this phenomenon is crucial for pilots and maintenance technicians alike, as it is essential to recognize the symptoms of an engine stall and respond appropriately to ensure safety and restore normal operation. The other options do not accurately reflect the behavior of an engine during a stall. For instance, an engine does not automatically increase speed and does not perform a system check or enter a standby state. Instead, the main characteristic of an engine stall is the failure to produce adequate power.