What is NACp in ADS-B data?
NACp is an aircraft-reported position accuracy category. Low NACp can be a useful signal for GNSS interference analysis, but it needs context.
NACp is the ADS-B Navigation Accuracy Category for Position. It reports the aircraft position accuracy category, commonly used to identify degraded GPS/GNSS accuracy patterns across regions.
NACp stands for Navigation Accuracy Category for Position. It is an ADS-B field that indicates the position accuracy category reported by the aircraft.
For GPS/GNSS interference analysis, NACp is useful because interference often appears as a drop in reported navigation accuracy across many aircraft in the same region. The pattern matters more than one isolated aircraft report.
How to use NACp responsibly
- Compare many aircraft over a region, not one aircraft in isolation.
- Look at time windows such as 1 hour, 6 hours, 24 hours, and 7 days.
- Treat low NACp as an interference indicator, not proof of intent or source.
- Cross-check with receiver coverage and aircraft mix before drawing conclusions.
FAQ
What does low NACp mean?
Low NACp means the aircraft is reporting lower position accuracy. It may indicate GNSS interference, aircraft equipment issues, or other context-dependent causes.