diff --git a/docs/en/gps_compass/index.md b/docs/en/gps_compass/index.md
index 6b965d2fea..578e018871 100644
--- a/docs/en/gps_compass/index.md
+++ b/docs/en/gps_compass/index.md
@@ -196,6 +196,14 @@ It is possible to have low DOP (good satellite geometry) but still have high EPH
 
 EPH/EPV values therefore provide a more immediate and practical estimate of the actual GPS accuracy you can expect under current conditions.
 
+### GNSS Position Fusion
+
+GNSS position fusion will not begin until yaw alignment is established.
+If a magnetometer is available, the EKF aligns yaw using the magnetic heading, allowing GPS position fusion to start soon after boot.
+If no magnetometer is present, the system must rely on GPS yaw (from a dual-antenna setup) or movement-based yaw estimation.
+Until one of these provides a valid heading, the EKF will not start GPS position fusion, and the vehicle will remain in a “no position” state even though attitude data is valid.
+This behavior prevents large position errors that could occur when the yaw reference is uncertain.
+
 ## Developer Information
 
 - GPS/RTK-GPS