Normal Mode = Control N1
-The EEC controls N1 based on thrust lever angle (TLA).
-But it’s not a direct mapping , it also references other parameters (ambient pressure, temperature, Mach, bleed air, etc.) to calculate:
-If the thrust lever is here , the required N1 should be this value.
-The result: N1 is actively controlled to match the commanded thrust (accurate and adjusted for conditions).
Alternate Mode = Schedule N1
-If required data is not available, the EEC switches to scheduling N1 directly from a lookup table between TLA and N1.
Meaning:
-For this thrust lever angle , apply this scheduled N1 value.
-No adjustment for real performance conditions , less accurate.
-That’s why it’s called “schedule”: it’s just using a fixed mapping, not dynamic control.
-Control (Normal mode): EEC uses multiple parameters to control N1 precisely according to thrust lever position.
-Schedule (Alternate mode): EEC uses a fixed schedule (TLA → N1 table), less accurate and more basic.