diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2c464cbda..ef8b6ade3 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -99,6 +99,7 @@ find_package(SimGear 2.0.0 REQUIRED)
 
 check_include_file(unistd.h HAVE_UNISTD_H)
 check_include_file(sys/time.h HAVE_SYS_TIME_H)
+check_include_file(windows.h HAVE_WINDOWS_H)
 
 # definition depends on OSG version
 set(CMAKE_REQUIRED_INCLUDES ${OPENSCENEGRAPH_INCLUDE_DIRS})
@@ -152,7 +153,7 @@ if(WIN32)
         #     SET(WARNING_FLAGS "${WARNING_FLAGS} /wd${warning}")
         # endforeach(warning)
         
-        set(MSVC_FLAGS "-DNOMINMAX -D_USE_MATH_DEFINES -D_CRT_SECURE_NO_WARNINGS -D__CRT_NONSTDC_NO_WARNINGS")
+        set(MSVC_FLAGS "-DNOMINMAX -D_USE_MATH_DEFINES -D_CRT_SECURE_NO_WARNINGS -D_SCL_SECURE_NO_WARNINGS -D__CRT_NONSTDC_NO_WARNINGS")
     endif(MSVC)
 
     set(NOMINMAX 1)
diff --git a/src/Airports/simple.cxx b/src/Airports/simple.cxx
index c5ac75baf..a085fab57 100644
--- a/src/Airports/simple.cxx
+++ b/src/Airports/simple.cxx
@@ -456,9 +456,13 @@ void FGAirport::readTowerData(SGPropertyNode* aRoot)
   SGPropertyNode* twrNode = aRoot->getChild("tower")->getChild("twr");
   double lat = twrNode->getDoubleValue("lat"), 
     lon = twrNode->getDoubleValue("lon"), 
-    elevM = twrNode->getDoubleValue("elev-m");
-    
-  _tower_location = SGGeod::fromDegM(lon, lat, elevM);
+    elevM = twrNode->getDoubleValue("elev-m");  
+// tower elevation is AGL, not AMSL. Since we don't want to depend on the
+// scenery for a precise terrain elevation, we use the field elevation
+// (this is also what the apt.dat code does)
+  double fieldElevationM = geod().getElevationM();
+  
+  _tower_location = SGGeod::fromDegM(lon, lat, fieldElevationM + elevM);
 }
 
 bool FGAirport::buildApproach(Waypt* aEnroute, STAR* aSTAR, FGRunway* aRwy, WayptVec& aRoute)
diff --git a/src/Include/config_cmake.h.in b/src/Include/config_cmake.h.in
index de02ad902..4505aa2dc 100644
--- a/src/Include/config_cmake.h.in
+++ b/src/Include/config_cmake.h.in
@@ -17,6 +17,7 @@
 #define ENABLE_AUDIO_SUPPORT 1 
 
 #cmakedefine HAVE_SYS_TIME_H
+#cmakedefine HAVE_WINDOWS_H
 #cmakedefine HAVE_CULLSETTINGS_CLEAR_MASK
 
 #define VERSION "@FLIGHTGEAR_VERSION@"
diff --git a/src/Navaids/navrecord.hxx b/src/Navaids/navrecord.hxx
index 2773629f4..09abb6e97 100644
--- a/src/Navaids/navrecord.hxx
+++ b/src/Navaids/navrecord.hxx
@@ -33,14 +33,6 @@
 #define FG_DME_DEFAULT_RANGE 50 // nm
 #define FG_NAV_MAX_RANGE 300    // nm
 
-// FIXME - get rid of these, and use the real enum directly
-#define FG_NAV_VOR FGPositioned::VOR
-#define FG_NAV_NDB FGPositioned::NDB
-#define FG_NAV_ILS FGPositioned::ILS
-#define FG_NAV_ANY FGPositioned::INVALID
-
-typedef FGPositioned::Type fg_nav_types;
-
 // forward decls
 class FGRunway;
 class SGPropertyNode;