Definition
The startup sequence a GPS receiver performs when powered on, in which it runs internal self-checks on its hardware and software, confirms the database is valid, and then acquires satellite signals to establish a current position before being used for navigation.
Plain English
When you turn the GPS on, it checks itself, confirms its data is good, and finds enough satellites to know where it is — only then is it ready to navigate.
Context Anchor
Seen during GPS start-up, before using the navigator for route guidance, approaches, or position awareness.
Derivation
Test' refers to the receiver's built-in self-tests of its electronics and software. 'Initialization' comes from Latin 'initium' meaning 'beginning' — setting the unit to a known starting state, including a current position fix and a valid navigation database, before it can be trusted for flight.
Why Pilots Care
Confirms the receiver is working correctly and has a valid position fix so the pilot can safely rely on GPS guidance.
Intuition Check
Do not assume the GPS is ready just because the screen is on. Test and initialization means the unit is still checking itself and setting up for use.
Example Sentence 1
During preflight, the pilot watched the GPS run its test and initialization, confirmed the database was current, and waited for a valid position fix before taxiing.
Example Sentence 2
During test and initialization the receiver verified its systems and acquired enough satellites for navigation.