Definition
An electronic circuit or device that compares two input signals and produces an output indicating which is larger, or whether they are equal. In aviation systems, comparators are used to monitor agreement between redundant instruments or signals and to trigger a warning when the values differ by more than a set tolerance.
Plain English
A device that watches two signals side by side and flags it when they don't match. If both agree, all is well. If they disagree by too much, it sounds an alarm or lights a flag so the pilot knows something is off.
Context Anchor
Seen in aircraft instrument and avionics systems, especially where two sources should agree with each other.
Derivation
From the Latin 'comparare', meaning 'to compare' or 'to pair together'. The '-ator' ending means 'a thing that does the action'. So a comparator is literally 'a thing that compares'.
Why Pilots Care
Detects failures in backup systems before they produce misleading flight instrument indications.
Intuition Check
A comparator does not automatically prove which input is correct. It mainly tells you that the inputs do not agree closely enough.
Example Sentence 1
The ILS comparator warning illuminated on short final, alerting the crew that the two localizer receivers were no longer showing the same course information.
Example Sentence 2
When the left and right attitude signals diverged, the comparator light illuminated on the instrument panel.