General Authority of Civil Aviation (GACA) Aeronautical Information Publication (AIP) Practice Exam

What is the difference between soft and hard levels in EEC alternate mode?

1. Soft level requires manual intervention

2. Hard level disables autothrottle

3. Soft level changes to alternate mode automatically

4. Hard level has no thrust protection

The correct answer is: Soft level changes to alternate mode automatically

In the context of EEC (Electronic Engine Control) alternate mode, the correct choice highlights that soft level operation transitions to alternate mode automatically. This is significant because soft level is designed to provide continuity and stability in engine performance without requiring additional input from the pilot, allowing for a smoother transition during an engine control system anomaly. When an aircraft's EEC switches to a soft level, it maintains some level of automatic control, ensuring that crucial parameters for engine performance remain optimized, even in a non-normal situation. This contrasts with other operational levels, where manual intervention may be necessary to manage the aircraft's performance or to respond to system anomalies. This automatic aspect of soft level distinguishes it from hard level, which does not function in the same seamless manner and may require more direct pilot management. In hard level, the system often limits certain protections and automations that could otherwise help maintain performance, thus affecting the general handling characteristics of the aircraft in critical phases.