From 5480479e73de4de9287dc46360a8724912e27951 Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <andrew@tridgell.net>
Date: Sun, 4 Nov 2018 16:31:04 +1100
Subject: [PATCH] HAL_SITL: fixed SITL example progs

---
 libraries/AP_HAL_SITL/SITL_State.cpp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/libraries/AP_HAL_SITL/SITL_State.cpp b/libraries/AP_HAL_SITL/SITL_State.cpp
index e9dad34fdf..251e3942d6 100644
--- a/libraries/AP_HAL_SITL/SITL_State.cpp
+++ b/libraries/AP_HAL_SITL/SITL_State.cpp
@@ -508,6 +508,11 @@ void SITL_State::set_height_agl(void)
 {
     static float home_alt = -1;
 
+    if (!_sitl) {
+        // in example program
+        return;
+    }
+
     if (is_equal(home_alt, -1.0f) && _sitl->state.altitude > 0) {
         // remember home altitude as first non-zero altitude
         home_alt = _sitl->state.altitude;