What is the required airspeed for an airstart if attempting at sea level to 15,000 feet MSL?

The required airspeed for an airstart is generally based on the need to maintain adequate aerodynamic control while ensuring a successful restart of the engine in flight. At sea level to 15,000 feet MSL, a speed of 125 KIAS is typically recommended for an airstart.

This airspeed is sufficient for maintaining lift and control of the aircraft while also providing an effective margin above stall speed. It ensures that the aircraft remains within a safe operating envelope, allowing the pilot to manage any potential fluctuations in thrust or airflow as the engine attempts to restart.

In contrast, choosing a higher or lower airspeed could compromise control or negatively influence the restart process. For example, flying at an airspeed that is too low might result in a stall or insufficient airflow over the engine, while a higher airspeed might complicate the airstart due to increased aerodynamic forces on the aircraft and the engine. Therefore, selecting 125 KIAS aligns with best practices for executing an airstart in the specified altitude range.