Definition
Information represented by a continuously variable physical quantity, such as voltage, pressure, or the position of a needle, where the value can take any point along a smooth range rather than stepping between fixed numbers.
Plain English
Data shown by something that moves smoothly across a range — like a needle sweeping around a dial — instead of jumping between separate numbers on a screen.
Context Anchor
Seen in aircraft instrument, sensor, and avionics discussions, especially when a system measures something physical and sends that information to another part of the airplane.
Derivation
From the Greek 'analogos,' meaning 'proportional' or 'corresponding.' The data is called analog because the physical signal (a voltage, a needle position) is directly proportional to the thing being measured. That proportional relationship is the core idea.
Why Pilots Care
Many legacy aircraft still use analog signals for instruments and engine data; understanding them is essential for troubleshooting and reading older cockpits.
Analogy
A light dimmer is analog: as you slide it, the light can change smoothly from dim to bright. That is different from a simple switch that is only on or off.
Intuition Check
Analog does not simply mean “old-fashioned” or “a round dial.” Here it means information carried by a smooth, continuously changing value.
Example Sentence 1
The airspeed indicator on the training aircraft displays analog data, with the needle moving smoothly as speed changes.
Example Sentence 2
A mechanic uses a voltmeter to check analog data coming from the manifold pressure sensor.