diff --git a/src/Airports/GenAirports850/airport.cxx b/src/Airports/GenAirports850/airport.cxx
index 9b72e682..31b370c9 100644
--- a/src/Airports/GenAirports850/airport.cxx
+++ b/src/Airports/GenAirports850/airport.cxx
@@ -35,14 +35,12 @@ Airport::Airport( int c, char* def)
 
     code = c;
 
-	SG_LOG(SG_GENERAL, SG_DEBUG, "sscanf " << def);
     numParams = sscanf(def, "%d %d %d %s %ls", &altitude, &x, &y, tmp, d);
-    SG_LOG(SG_GENERAL, SG_DEBUG, "done ");
-	SG_LOG(SG_GENERAL, SG_DEBUG, "got " << altitude << ", " << tmp << ", " << d);
 
     altitude *= SG_FEET_TO_METER;
     icao = tmp;
     description = d;
+    boundary = NULL;
 }
 
 // TODO: fix OSG - it was nice, but unnecesary...
@@ -380,7 +378,14 @@ void Airport::BuildBtg(const string& root, const string_list& elev_src )
     {
         if ( runways[i]->IsPrecision() ) 
         {
-            runways[i]->BuildBtg( altitude, &rwy_polys, &rwy_tps, &rwy_lights, &accum, &apt_base, &apt_clearing );
+            if (boundary)
+            {
+                runways[i]->BuildBtg( altitude, &rwy_polys, &rwy_tps, &rwy_lights, &accum, NULL, NULL );
+            }
+            else
+            {
+                runways[i]->BuildBtg( altitude, &rwy_polys, &rwy_tps, &rwy_lights, &accum, &apt_base, &apt_clearing );
+            }
 	    }
     }
 
@@ -397,7 +402,14 @@ void Airport::BuildBtg(const string& root, const string_list& elev_src )
     {
         for (i=0; i<helipads.size(); i++ )
         {
-            helipads[i]->BuildBtg( altitude, &rwy_polys, &rwy_tps, &rwy_lights, &accum, &apt_base, &apt_clearing );
+            if (boundary)
+            {
+                helipads[i]->BuildBtg( altitude, &rwy_polys, &rwy_tps, &rwy_lights, &accum, NULL, NULL );
+            }
+            else
+            {
+                helipads[i]->BuildBtg( altitude, &rwy_polys, &rwy_tps, &rwy_lights, &accum, &apt_base, &apt_clearing );
+            }
         }
     }
     // Build the pavements
@@ -406,8 +418,15 @@ void Airport::BuildBtg(const string& root, const string_list& elev_src )
         for ( i=0; i<pavements.size(); i++ )
         {
             SG_LOG(SG_GENERAL, SG_ALERT, "Build Pavement Poly " << i << ": " << pavements[i]->GetDescription());
-            pavements[i]->BuildBtg( altitude, &pvmt_polys, &pvmt_tps, &accum, &apt_base, &apt_clearing );
-            // AddFeatures( pavements[i]->GetMarkings() );
+
+            if (boundary)
+            {
+                pavements[i]->BuildBtg( altitude, &pvmt_polys, &pvmt_tps, &accum, NULL, NULL );
+            }
+            else
+            {
+                pavements[i]->BuildBtg( altitude, &pvmt_polys, &pvmt_tps, &accum, &apt_base, &apt_clearing );
+            }
         }
     }
     else
@@ -415,6 +434,12 @@ void Airport::BuildBtg(const string& root, const string_list& elev_src )
         SG_LOG(SG_GENERAL, SG_ALERT, "no pavements");
     }
 
+    // build the base and clearing if there's a boundary
+    if (boundary)
+    {
+        boundary->BuildBtg( altitude, &apt_base, &apt_clearing );
+    }
+
     if ( apt_base.total_size() == 0 )
     {
         SG_LOG(SG_GENERAL, SG_ALERT, "no airport points generated");
diff --git a/src/Airports/GenAirports850/airport.hxx b/src/Airports/GenAirports850/airport.hxx
index dc3ec359..86371b09 100644
--- a/src/Airports/GenAirports850/airport.hxx
+++ b/src/Airports/GenAirports850/airport.hxx
@@ -57,6 +57,11 @@ public:
         }
     }
 
+    void SetBoundary( ClosedPoly* bndry )
+    {
+        boundary = bndry;
+    }
+
     void AddWindsock( Windsock* windsock )
     {
         windsocks.push_back( windsock );
@@ -90,6 +95,7 @@ private:
     BeaconList      beacons;
     SignList        signs;
     HelipadList     helipads;
+    ClosedPoly*     boundary;
 };
 
 typedef std::vector <Airport *> AirportList;
diff --git a/src/Airports/GenAirports850/closedpoly.cxx b/src/Airports/GenAirports850/closedpoly.cxx
index d3249602..da895200 100644
--- a/src/Airports/GenAirports850/closedpoly.cxx
+++ b/src/Airports/GenAirports850/closedpoly.cxx
@@ -14,12 +14,31 @@
 #include "convex_hull.hxx"
 #include "closedpoly.hxx"
 
+ClosedPoly::ClosedPoly( char* desc )
+{
+    is_pavement = false;
+
+    if ( desc )
+    {
+        description = desc;
+    }
+    else
+    {
+        description = "none";
+    }
+        
+    boundary = NULL;
+    cur_contour = NULL;
+    cur_feature = NULL;
+}
 
 ClosedPoly::ClosedPoly( int st, float s, float th, char* desc )
 {
     surface_type = st;
     smoothness   = s;
     texture_heading = th;
+    is_pavement = true;
+
     if ( desc )
     {
         description = desc;
@@ -43,31 +62,28 @@ void ClosedPoly::AddNode( BezNode* node )
     }
     cur_contour->push_back( node );
 
-
     SG_LOG(SG_GENERAL, SG_DEBUG, "CLOSEDPOLY::ADDNODE : (" << node->GetLoc().x() << "," << node->GetLoc().y() << ")");
 
-
-    // TODO: Create ONE linear feature for each contour.  
-    // Parse the polys in linear feature
-    // if recording a linear feature on the pavement, add this node
-    // to it as well
-    // TODO: just doing marking now, need lighting as well
-    if (!cur_feature)
+    // For pavement polys, add a linear feature for each contour
+    if (is_pavement)
     {
-        string feature_desc = description + ":";
-        if (boundary)
+        if (!cur_feature)
         {
-            feature_desc += "hole";
-        }
-        else
-        {
-            feature_desc += "boundary";
-        }
+            string feature_desc = description + ":";
+            if (boundary)
+            {
+                feature_desc += "hole";
+            }
+            else
+            {
+                feature_desc += "boundary";
+            }
 
-        SG_LOG(SG_GENERAL, SG_DEBUG, "   Adding node (" << node->GetLoc().x() << "," << node->GetLoc().y() << ") to current linear feature " << cur_feature);
-        cur_feature = new LinearFeature(feature_desc, 1.0f );
-    } 
-    cur_feature->AddNode( node );
+            SG_LOG(SG_GENERAL, SG_DEBUG, "   Adding node (" << node->GetLoc().x() << "," << node->GetLoc().y() << ") to current linear feature " << cur_feature);
+            cur_feature = new LinearFeature(feature_desc, 1.0f );
+        } 
+        cur_feature->AddNode( node );
+    }
 }
 
 void ClosedPoly::CreateConvexHull( void )
@@ -77,17 +93,20 @@ void ClosedPoly::CreateConvexHull( void )
     Point3D    p;
     int        i;
 
-    if (boundary->size() > 2){
+    if (boundary->size() > 2)
+    {
         for (i=0; i<boundary->size(); i++)
         {
-
             p = boundary->at(i)->GetLoc();
             nodes.push_back( p );
         }
         convexHull = convex_hull( nodes );
         hull = convexHull.get_contour(0);
-    } else
+    } 
+    else
+    {
         SG_LOG(SG_GENERAL, SG_ALERT, "Boundary size too small: " << boundary->size() << ". Ignoring..." );
+    }
 }
 
 int ClosedPoly::CloseCurContour()
@@ -281,9 +300,6 @@ void ClosedPoly::ConvertContour( BezContour* src, point_list *dst )
             SG_LOG(SG_GENERAL, SG_DEBUG, "adding Linear Anchor node at (" << curLoc.x() << "," << curLoc.y() << ")");
         }
     }
-
-    // Add the first point again?
-    // dst->push_back( src->at(0)->GetLoc() );
 }
 
 void ExpandPoint( Point3D *prev, Point3D *cur, Point3D *next, double expand_by, double *heading, double *offset )
@@ -459,7 +475,7 @@ int ClosedPoly::Finish()
     // error handling
     if (boundary == NULL)
     {
-        SG_LOG(SG_GENERAL, SG_DEBUG, "no boundary");
+        SG_LOG(SG_GENERAL, SG_ALERT, "no boundary");
     }
 
     SG_LOG(SG_GENERAL, SG_DEBUG, "Converting a poly with " << holes.size() << " holes");
@@ -485,7 +501,7 @@ int ClosedPoly::Finish()
     delete boundary;
     boundary = NULL;
 
-    // The convert the hole contours
+    // and the hole contours
     holes.clear();
 }
 
@@ -579,84 +595,109 @@ int ClosedPoly::BuildBtg( float alt_m, superpoly_list* rwy_polys, texparams_list
     string material;
     int j, k;
 
-    switch( surface_type )
+    if (is_pavement)
     {
-        case 1:
-            material = "pa_tiedown";
-            break;
+        switch( surface_type )
+        {
+            case 1:
+                material = "pa_tiedown";
+                break;
 
-        case 2:
-            material = "pc_tiedown";
-            break;
+            case 2:
+                material = "pc_tiedown";
+                break;
 
-        case 3:
-            material = "grass_rwy";
-            break;
-// TODO Differentiate more here:
-        case 4:
-        case 5:
-        case 12:
-        case 13:
-        case 14:
-        case 15:
-            material = "grass_rwy";
-            break;
+            case 3:
+                material = "grass_rwy";
+                break;
+            
+            // TODO Differentiate more here:
+            case 4:
+            case 5:
+            case 12:
+            case 13:
+            case 14:
+            case 15:
+                material = "grass_rwy";
+                break;
 
-        default:
-            SG_LOG(SG_GENERAL, SG_ALERT, "ClosedPoly::BuildBtg: unknown surface type " << surface_type );
-            exit(1);
+            default:
+                SG_LOG(SG_GENERAL, SG_ALERT, "ClosedPoly::BuildBtg: unknown surface type " << surface_type );
+                exit(1);
+        }
+
+        // verify the poly has been generated
+        if ( pre_tess.contours() )    
+        {
+            SG_LOG(SG_GENERAL, SG_DEBUG, "BuildBtg: original poly has " << pre_tess.contours() << " contours");
+    
+            // do this before clipping and generating the base
+        	pre_tess = remove_dups( pre_tess );
+            pre_tess = reduce_degeneracy( pre_tess );
+
+            for (int c=0; c<pre_tess.contours(); c++)
+            {
+                for (int pt=0; pt<pre_tess.contour_size(c); pt++)
+                {
+                    SG_LOG(SG_GENERAL, SG_DEBUG, "BuildBtg: contour " << c << " pt " << pt << ": (" << pre_tess.get_pt(c, pt).x() << "," << pre_tess.get_pt(c, pt).y() << ")" );
+                }
+            }
+
+
+            TGSuperPoly sp;
+            TGTexParams tp;
+
+            TGPolygon clipped = tgPolygonDiff( pre_tess, *accum );
+            SG_LOG(SG_GENERAL, SG_DEBUG, "BuildBtg: clipped poly has " << clipped.contours() << " contours");
+
+            TGPolygon split   = tgPolygonSplitLongEdges( clipped, 400.0 );
+            SG_LOG(SG_GENERAL, SG_DEBUG, "BuildBtg: split poly has " << split.contours() << " contours");
+
+            sp.erase();
+            sp.set_poly( split );
+            sp.set_material( material );
+            //sp.set_flag("taxi");
+
+            rwy_polys->push_back( sp );
+            SG_LOG(SG_GENERAL, SG_DEBUG, "clipped = " << clipped.contours());
+            *accum = tgPolygonUnion( pre_tess, *accum );
+            tp = TGTexParams( pre_tess.get_pt(0,0), 5.0, 5.0, texture_heading );
+            texparams->push_back( tp );
+
+            if ( apt_base )
+            {           
+                ExpandContour( hull, base, 20.0 );
+                ExpandContour( hull, safe_base, 50.0 );
+        
+                // add this to the airport clearing
+                *apt_clearing = tgPolygonUnion( safe_base, *apt_clearing);
+
+                // and add the clearing to the base
+                *apt_base = tgPolygonUnion( base, *apt_base );
+            }
+        }
     }
 
+    // clean up to save ram : we're done here...
+    return 1;
+}
+
+int ClosedPoly::BuildBtg( float alt_m, TGPolygon* apt_base, TGPolygon* apt_clearing )
+{
+    TGPolygon base, safe_base;
+
     // verify the poly has been generated
     if ( pre_tess.contours() )    
     {
         SG_LOG(SG_GENERAL, SG_DEBUG, "BuildBtg: original poly has " << pre_tess.contours() << " contours");
     
-        // do this before clipping and generating the base
-    	pre_tess = remove_dups( pre_tess );
-        pre_tess = reduce_degeneracy( pre_tess );
-
-        for (int c=0; c<pre_tess.contours(); c++)
-        {
-            for (int pt=0; pt<pre_tess.contour_size(c); pt++)
-            {
-                SG_LOG(SG_GENERAL, SG_DEBUG, "BuildBtg: contour " << c << " pt " << pt << ": (" << pre_tess.get_pt(c, pt).x() << "," << pre_tess.get_pt(c, pt).y() << ")" );
-            }
-        }
-
-
-        TGSuperPoly sp;
-        TGTexParams tp;
-
-        TGPolygon clipped = tgPolygonDiff( pre_tess, *accum );
-        SG_LOG(SG_GENERAL, SG_DEBUG, "BuildBtg: clipped poly has " << clipped.contours() << " contours");
-
-        TGPolygon split   = tgPolygonSplitLongEdges( clipped, 400.0 );
-        SG_LOG(SG_GENERAL, SG_DEBUG, "BuildBtg: split poly has " << split.contours() << " contours");
-
-        sp.erase();
-        sp.set_poly( split );
-        sp.set_material( material );
-        //sp.set_flag("taxi");
-
-        rwy_polys->push_back( sp );
-        SG_LOG(SG_GENERAL, SG_DEBUG, "clipped = " << clipped.contours());
-        *accum = tgPolygonUnion( pre_tess, *accum );
-        tp = TGTexParams( pre_tess.get_pt(0,0), 5.0, 5.0, texture_heading );
-        texparams->push_back( tp );
-
-        ExpandContour( hull, base, 20.0 );
-        ExpandContour( hull, safe_base, 50.0 );
+        hull = pre_tess.get_contour(0);
+        ExpandContour( hull, safe_base, 20.0 );
         
         // add this to the airport clearing
         *apt_clearing = tgPolygonUnion( safe_base, *apt_clearing);
 
         // and add the clearing to the base
-        *apt_base = tgPolygonUnion( base, *apt_base );
+        *apt_base = tgPolygonUnion( pre_tess, *apt_base );
     }
-
-    // clean up to save ram : we're done here...
-
-
-    return 1;
 }
diff --git a/src/Airports/GenAirports850/closedpoly.hxx b/src/Airports/GenAirports850/closedpoly.hxx
index 368ce0d8..08982fdf 100644
--- a/src/Airports/GenAirports850/closedpoly.hxx
+++ b/src/Airports/GenAirports850/closedpoly.hxx
@@ -18,13 +18,20 @@ using std::string;
 class ClosedPoly
 {
 public:
+    ClosedPoly( char* desc );
     ClosedPoly( int st, float s, float th, char* desc );
     
     inline string GetDescription() { return description; }
     void AddNode( BezNode* node );
     int  CloseCurContour();
     int  Finish();
+
     int  BuildOsg( osg::Group* airport );
+
+    // Build BTG for airport base for airports with boundary
+    int  BuildBtg( float alt_m, TGPolygon* apt_base, TGPolygon* apt_clearing );
+
+    // Build BTG for pavements for airports with no boundary
     int  BuildBtg( float alt_m, superpoly_list* rwy_polys, texparams_list* texparams, TGPolygon* accum, TGPolygon* apt_base, TGPolygon* apt_clearing );
 
     FeatureList* GetFeatures()
@@ -40,6 +47,7 @@ private:
     osg::DrawArrays* CreateOsgPrimitive( point_list contour, osg::Vec3Array* vpave );
     void ExpandContour( point_list& src, TGPolygon& dst, double dist );
 
+    bool   is_pavement;
     int    surface_type;
     float  smoothness;
     float  texture_heading;
diff --git a/src/Airports/GenAirports850/helipad.cxx b/src/Airports/GenAirports850/helipad.cxx
index 28b094a7..77a31027 100644
--- a/src/Airports/GenAirports850/helipad.cxx
+++ b/src/Airports/GenAirports850/helipad.cxx
@@ -114,17 +114,20 @@ void Helipad::BuildBtg( float alt_m,
 
 
     // generate area around helipad
-    TGPolygon base, safe_base;
-    base      = gen_runway_area_w_extend( 0.0, maxsize * 0.25 , 0.0, 0.0, maxsize * 0.25 );
+    if (apt_base)
+    {
+        TGPolygon base, safe_base;
+        base      = gen_runway_area_w_extend( 0.0, maxsize * 0.25 , 0.0, 0.0, maxsize * 0.25 );
 
-    // also clear a safe area around the pad
-    safe_base = gen_runway_area_w_extend( 0.0, maxsize * 0.5, 0.0, 0.0, maxsize * 0.5 );
+        // also clear a safe area around the pad
+        safe_base = gen_runway_area_w_extend( 0.0, maxsize * 0.5, 0.0, 0.0, maxsize * 0.5 );
 
-    // add this to the airport clearing
-    *apt_clearing = tgPolygonUnion(safe_base, *apt_clearing);
+        // add this to the airport clearing
+        *apt_clearing = tgPolygonUnion(safe_base, *apt_clearing);
 
-    // and add the clearing to the base
-    *apt_base = tgPolygonUnion( base, *apt_base );
+        // and add the clearing to the base
+        *apt_base = tgPolygonUnion( base, *apt_base );
+    }
 
     // Now generate the helipad lights
     superpoly_list s = gen_helipad_lights();
diff --git a/src/Airports/GenAirports850/lights.cxx b/src/Airports/GenAirports850/lights.cxx
index ff38c137..67c9f38e 100644
--- a/src/Airports/GenAirports850/lights.cxx
+++ b/src/Airports/GenAirports850/lights.cxx
@@ -2578,7 +2578,7 @@ superpoly_list Runway::gen_malsx( float alt_m, const string& kind, bool recip )
 
 
 // top level runway light generator
-void Runway::gen_runway_lights( float alt_m, superpoly_list *lights, TGPolygon *apt_base ) {
+void Runway::gen_runway_lights( float alt_m, superpoly_list *lights ) {
 
     unsigned int i;
 
diff --git a/src/Airports/GenAirports850/parser.cxx b/src/Airports/GenAirports850/parser.cxx
index 66bb9261..5eac64e7 100644
--- a/src/Airports/GenAirports850/parser.cxx
+++ b/src/Airports/GenAirports850/parser.cxx
@@ -211,6 +211,30 @@ ClosedPoly* Parser::ParsePavement( char* line )
     return poly;
 }
 
+ClosedPoly* Parser::ParseBoundary( char* line )
+{
+    ClosedPoly* poly;
+    char  desc[256];
+    char  *d = NULL;
+    int   numParams;
+
+    numParams = sscanf(line, "%ls", desc);
+
+    if (numParams == 1)
+    {
+        d = strstr(line,desc);
+    }
+    else
+    {
+        d = "none";
+    }
+
+    SG_LOG(SG_GENERAL, SG_DEBUG, "Creating Closed Poly for airport boundary : " << d);
+    poly = new ClosedPoly(d);
+
+    return poly;
+}
+
 int Parser::SetState( int state )
 {
     // if we are currently parsing pavement, the oly way we know we are done 
@@ -223,6 +247,14 @@ int Parser::SetState( int state )
         cur_pavement = NULL;
     } 
 
+    if ( cur_airport && cur_state == STATE_PARSE_BOUNDARY )
+    {
+        SG_LOG(SG_GENERAL, SG_DEBUG, "Closing and Adding boundary");
+        cur_boundary->Finish();
+        cur_airport->SetBoundary( cur_boundary );
+        cur_boundary = NULL;
+    } 
+
     cur_state = state;
 }
 
@@ -297,8 +329,7 @@ int Parser::ParseLine(char* line)
 
             case BOUNDRY_CODE:
                 SetState( STATE_PARSE_BOUNDARY );
-                SG_LOG(SG_GENERAL, SG_DEBUG, "Parsing airport boundary: " << line);
-//              ParseBoundry(line); 
+                cur_boundary = ParseBoundary( line ); 
                 break;
 
             case NODE_CODE:
@@ -317,6 +348,10 @@ int Parser::ParseLine(char* line)
                     {
                         cur_feat->AddNode( prev_node );
                     }
+                    else if ( cur_state == STATE_PARSE_BOUNDARY )
+                    {
+                        cur_boundary->AddNode( prev_node );
+                    }
                 }
 
                 prev_node = cur_node;
@@ -340,6 +375,19 @@ int Parser::ParseLine(char* line)
                     }
                     cur_pavement->CloseCurContour();
                 }
+                else if ( cur_state == STATE_PARSE_BOUNDARY )
+                {
+                    if (cur_node != prev_node)
+                    {
+                        cur_boundary->AddNode( prev_node );
+                        cur_boundary->AddNode( cur_node );
+                    }
+                    else
+                    {
+                        cur_boundary->AddNode( cur_node );
+                    }
+                    cur_boundary->CloseCurContour();
+                }
                 else if ( cur_state == STATE_PARSE_FEATURE )
                 {
                     if (cur_node != prev_node)
diff --git a/src/Airports/GenAirports850/parser.hxx b/src/Airports/GenAirports850/parser.hxx
index 199fcd44..0932b326 100644
--- a/src/Airports/GenAirports850/parser.hxx
+++ b/src/Airports/GenAirports850/parser.hxx
@@ -59,8 +59,16 @@ public:
     {
         filename        = f;
         cur_airport     = NULL;
+        cur_runway      = NULL;
+        cur_waterrunway = NULL;
+        cur_helipad     = NULL;
         cur_pavement    = NULL;
+        cur_boundary    = NULL;
         cur_feat        = NULL;
+        cur_object      = NULL;
+        cur_windsock    = NULL;
+        cur_beacon      = NULL;
+        cur_sign        = NULL;
         prev_node       = NULL;
         cur_state       = STATE_NONE;
     }
@@ -76,10 +84,12 @@ private:
     LinearFeature*  ParseFeature( char* line );
     ClosedPoly*     ParsePavement( char* line );
     osg::Geode*     ParseRunway(char* line );
+    ClosedPoly*     ParseBoundary( char* line );
+
     int             ParseLine( char* line );
 
-//    int ParseBoundry(char* line, Node* airport);
-
+    BezNode*        prev_node;
+    int             cur_state;
     string          filename;
 
     // a polygon conists of an array of contours 
@@ -89,16 +99,14 @@ private:
     WaterRunway*    cur_waterrunway;
     Helipad*        cur_helipad;
     ClosedPoly*     cur_pavement;
+    ClosedPoly*     cur_boundary;
     LinearFeature*  cur_feat;
-    BezNode*        prev_node;
     LightingObj*    cur_object;
     Windsock*       cur_windsock;
     Beacon*         cur_beacon;
     Sign*           cur_sign;
 
     AirportList     airports;
-
-    int cur_state;
 };
 
 #endif
diff --git a/src/Airports/GenAirports850/runway.cxx b/src/Airports/GenAirports850/runway.cxx
index ba08ab29..678084dd 100644
--- a/src/Airports/GenAirports850/runway.cxx
+++ b/src/Airports/GenAirports850/runway.cxx
@@ -170,7 +170,7 @@ int Runway::BuildBtg( float alt_m, superpoly_list* rwy_polys, texparams_list* te
         case 2: // concrete
             SG_LOG( SG_GENERAL, SG_ALERT, "Build Runway: asphalt or concrete" << rwy.surface);
             gen_rwy( alt_m, material, rwy_polys, texparams, accum );
-            gen_runway_lights( alt_m, rwy_lights, apt_base );
+            gen_runway_lights( alt_m, rwy_lights );
             break;
     
         case 3: // Grass
@@ -178,7 +178,7 @@ int Runway::BuildBtg( float alt_m, superpoly_list* rwy_polys, texparams_list* te
         case 5: // Gravel
             SG_LOG( SG_GENERAL, SG_ALERT, "Build Runway: Turf, Dirt or Gravel" << rwy.surface );
 	        gen_simple_rwy( alt_m, material, rwy_polys, texparams, accum );
-                gen_runway_lights( alt_m, rwy_lights, apt_base );
+                gen_runway_lights( alt_m, rwy_lights );
             break;
 
         case 12: // dry lakebed
@@ -202,15 +202,18 @@ int Runway::BuildBtg( float alt_m, superpoly_list* rwy_polys, texparams_list* te
             break;
     }    
 
-    // generate area around runways
-    base      = gen_runway_area_w_extend( 0.0, rwy.width * 0.25, -rwy.overrun[0], -rwy.overrun[1], rwy.width * 0.25);
+    if (apt_base)
+    {
+        // generate area around runways
+        base      = gen_runway_area_w_extend( 0.0, rwy.width * 0.25, -rwy.overrun[0], -rwy.overrun[1], rwy.width * 0.25);
 
-    // also clear a safe area around the runway
-    safe_base = gen_runway_area_w_extend( 0.0, rwy.width, -rwy.overrun[0], -rwy.overrun[1], rwy.width );
+        // also clear a safe area around the runway
+        safe_base = gen_runway_area_w_extend( 0.0, rwy.width, -rwy.overrun[0], -rwy.overrun[1], rwy.width );
 
-    // add this to the airport clearing
-    *apt_clearing = tgPolygonUnion(safe_base, *apt_clearing);
+        // add this to the airport clearing
+        *apt_clearing = tgPolygonUnion(safe_base, *apt_clearing);
 
-    // and add the clearing to the base
-    *apt_base = tgPolygonUnion( base, *apt_base );
+        // and add the clearing to the base
+        *apt_base = tgPolygonUnion( base, *apt_base );
+    }
 }
diff --git a/src/Airports/GenAirports850/runway.hxx b/src/Airports/GenAirports850/runway.hxx
index 25086d92..26d2ee6b 100644
--- a/src/Airports/GenAirports850/runway.hxx
+++ b/src/Airports/GenAirports850/runway.hxx
@@ -130,7 +130,7 @@ private:
                          texparams_list* texparams,
                          TGPolygon* accum, int marking);
 
-    void gen_runway_lights( float alt_m, superpoly_list* lights, TGPolygon* apt_base );
+    void gen_runway_lights( float alt_m, superpoly_list* lights );
 
     Point3D gen_runway_light_vector( double angle, bool recip );
     superpoly_list gen_runway_edge_lights( bool recip );