Definition
A descriptive phrase indicating that something operates, responds, or varies by significantly different amounts depending on conditions or inputs, rather than uniformly. In the Airplane Flying Handbook context, it describes how cockpit instruments, controls, or systems can produce noticeably different outputs or readings in response to relatively small differences in input or situation.
Plain English
Means something behaves in a way where small changes produce noticeably different results — it doesn't react the same way in every situation.
Context Anchor
Seen in discussions of aileron design and how roll control is made smoother and easier to coordinate.
Derivation
From Latin 'differentia' meaning 'difference.' 'Differential' here means 'showing or based on differences.' So 'highly differential' simply means 'strongly varying based on differences' — not uniform, not the same across the board.
Why Pilots Care
If ailerons move in a highly differential manner, the airplane may need less rudder input during a turn because the design helps reduce unwanted yaw.
Analogy
Think of a pair of doors linked together so that when one opens wide, the other opens only a little. They are connected, but they do not move equally.
Intuition Check
Do not read highly differential manner as simply “very different” in a general sense. Here it means a deliberate unequal movement built into a paired aircraft control system.
Example Sentence 1
The control surface responded in a highly differential manner, with small stick inputs producing large changes near the stall but only minor changes at cruise speed.
Example Sentence 2
During the engine failure drill, power was reduced in a highly differential manner to maintain directional control.