What signifies the completion of a successful engine start?

The successful completion of an engine start is signified by verifying proper fuel flow and ignition. This step ensures that the engine has received the necessary fuel and has successfully ignited it, which is critical for starting the engine. If fuel flow is correct and there is ignition, it confirms that the engine is functioning as intended and is ready for further operations.

Monitoring engine temperature is important for assessing the engine's performance and ensuring it operates within safe limits, but it does not directly indicate that the start process has been successfully completed. Achieving cruising speed and maintaining altitude are phases of flight that occur after the engine has been started and requires additional systems to be functional. Therefore, they are not indicative of a successful engine start, but rather of progressing through later stages of flight after the engine has started.