Definition
Test circuitry permanently installed within an aircraft system or component that automatically monitors its own operation, detects faults, and reports the results without requiring external test gear. Commonly abbreviated BITE.
Plain English
Equipment that checks itself. The testing tools are built into the system, so it can find its own faults and tell the crew or technician what's wrong.
Context Anchor
Seen during maintenance checks and cockpit self-tests of aircraft electronic systems.
Why Pilots Care
Allows quick detection of equipment problems before or during flight, shortening troubleshooting time and supporting safer operations.
Intuition Check
Do not think of Built-In Test Equipment as a separate toolbox carried on the airplane. It is the test feature already installed inside the system being checked.
Example Sentence 1
The flight management system's built-in test equipment flagged a fault in the navigation receiver during the preflight check.
Example Sentence 2
Maintenance used the Built-In Test Equipment results to isolate the faulty sensor without connecting external test gear.