What is an indication of a hung start?

A hung start is indicated by a slow rising ITT (Inter Turbine Temperature) because it suggests that the engine is trying to start, but the combustion process is not occurring efficiently or as expected. During a normal start, the ITT would rise quickly due to the ignition of fuel in the engine's combustion section. However, if the ITT rises slowly, it implies that the fuel-air mixture may not be creating enough thrust for efficient ignition, which can lead to a condition where the engine does not reach its operational parameters and stalls out.

In the context of assessing engine performance during start-up, the slow rise is a critical indicator pointing to potential issues, particularly in situations where the engine is meant to transition smoothly from start to operational running. Recognizing this can help in troubleshooting and preventing further complications during operation. The other choices do not signify a hung start as clearly or directly as the slow rising ITT does.