From 5ea0ef39cdd50e8b634dd38e72e48844e660a11c Mon Sep 17 00:00:00 2001
From: Paul Riseborough <p_riseborough@live.com.au>
Date: Tue, 9 Feb 2016 07:44:34 +1100
Subject: [PATCH] EKF: Update declination fusion logic

We do not need to run declination fusion if 3-axis mag fusion is not being used.
---
 EKF/control.cpp | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/EKF/control.cpp b/EKF/control.cpp
index 104a5f21bd..ae34a76504 100644
--- a/EKF/control.cpp
+++ b/EKF/control.cpp
@@ -111,11 +111,11 @@ void Ekf::controlFusionModes()
 	}
 
 	// if we are using 3-axis magnetometer fusion, but without external aiding, then the declination needs to be fused as an observation to prevent long term heading drift
-	if (_control_status.flags.mag_3D && _control_status.flags.gps) {
-		_control_status.flags.mag_dec = false;
+	if (_control_status.flags.mag_3D && !_control_status.flags.gps) {
+		_control_status.flags.mag_dec = true;
 
 	} else {
-		_control_status.flags.mag_dec = true;
+		_control_status.flags.mag_dec = false;
 	}
 }