Definition
Onboard software functions in a Synthetic Vision Guidance System (SVGS) that continuously check the integrity and accuracy of the aircraft's position solution to confirm it is precise enough to support the displayed synthetic guidance during a low-visibility approach. If the position quality drops below the required level, these monitors alert the crew so the synthetic vision symbology cannot be used for operational credit.
Plain English
Background checks built into the system that constantly ask, 'Do we really know where the aircraft is, accurately enough to trust this picture?' If the answer becomes no, the system warns the pilot.
Context Anchor
Seen in Synthetic Vision Guidance System discussions, especially where the system is used to support precise approach and runway guidance.
Derivation
Three plain-English ideas joined together. 'High precision' means tightly accurate. 'Position assurance' means confidence that the reported aircraft position is trustworthy. 'Monitors' are watchdog functions that keep checking in the background. Put together, they are the watchdogs that guarantee the position shown is good enough to fly by.
Why Pilots Care
They protect against misleading position data that could result in an unsafe approach or landing.
Grounding Statement
The system must confirm the airplane’s position before it lets the pilot rely on the synthetic runway or guidance path.
Intuition Check
Do not read “monitors” as cockpit screens. Here, monitors means automatic safety checks inside the system. Do not read “assurance” as a vague promise. Here, it means the system is actively checking that the position is good enough to use.
Example Sentence 1
Before the SVGS approach can be flown for operational credit, the high precision position assurance monitors must be active and reporting normal status.
Example Sentence 2
When the high precision position assurance monitors detected degraded accuracy, the system automatically downgraded to a non-precision mode.