From 4e928bf2940a09afcb6ce8de136e8afa53d462ba Mon Sep 17 00:00:00 2001
From: Paul Riseborough <p-riseborough@live.com.au>
Date: Thu, 15 Oct 2015 21:54:45 +1100
Subject: [PATCH] AP_NavEKF2: Fix bug preventing pre-takeoff reference
 measurements

---
 libraries/AP_NavEKF2/AP_NavEKF2_VehicleStatus.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libraries/AP_NavEKF2/AP_NavEKF2_VehicleStatus.cpp b/libraries/AP_NavEKF2/AP_NavEKF2_VehicleStatus.cpp
index 70db557346..a73f8f5df0 100644
--- a/libraries/AP_NavEKF2/AP_NavEKF2_VehicleStatus.cpp
+++ b/libraries/AP_NavEKF2/AP_NavEKF2_VehicleStatus.cpp
@@ -351,7 +351,7 @@ void NavEKF2_core::detectFlight()
     prevInFlight = inFlight;
 
     // Store vehicle height and range prior to takeoff for use in post takeoff checks
-    if (!onGround && !prevOnGround) {
+    if (onGround && prevOnGround) {
         // store vertical position at start of flight to use as a reference for ground relative checks
         posDownAtTakeoff = stateStruct.position.z;
         // store the range finder measurement which will be used as a reference to detect when we have taken off