Which of the following is a possible display indication of engine failure in flight?

Loss of power or airspeed accompanied by MASTER WARN lights or tones is indeed a significant indication of engine failure in flight. When an engine fails, the pilot will notice a sudden decrease in thrust or acceleration, which translates into a loss of power and a reduction in airspeed. The MASTER WARNING system is designed to alert the pilot to serious malfunctions or emergencies, such as engine failure, through visual indicators and audible tones. Therefore, the combination of these indicators is a critical signal that the engine has failed and requires immediate attention and action by the pilot to manage the emergency effectively.

In contrast, the other options do not accurately represent typical indications of engine failure. Unresponsive cockpit controls do not specifically indicate engine failure, as they could relate to other issues within the aircraft systems. High N1 and high ITT readings suggest that the engine is functioning normally, as these parameters would typically indicate healthy operational performance rather than failure. Finally, stable engine performance would be inconsistent with engine failure, as it implies that the engine is operating within normal limits, thus ruling out any engine issues.