diff --git a/nasal/dialogs/route.nas b/nasal/dialogs/route.nas
index 0c1e5a2..99766c0 100644
--- a/nasal/dialogs/route.nas
+++ b/nasal/dialogs/route.nas
@@ -33,7 +33,7 @@ var RouteDialog = {
         }));
 
         # Set listeners for distance fields for calculate altitude change
-        for (var i = 0; i < obj.maxRouteWaypoints; i = i + 1) {
+        for (var i = 0; i < obj.maxRouteWaypoints; i += 1) {
             append(obj.listeners, setlistener(obj.addonNodePath ~ "/addon-devel/route/wpt[" ~ i ~ "]/distance-m", func () {
                 obj.calculateAltChangeAndTotals();
             }));
@@ -62,7 +62,7 @@ var RouteDialog = {
         var isRouteMode = 1;
         var aircraft = Aircraft.getSelected(me.addon, isRouteMode);
 
-        for (var i = 0; i < me.maxRouteWaypoints; i = i + 1) {
+        for (var i = 0; i < me.maxRouteWaypoints; i += 1) {
             var distance = getprop(me.addonNodePath ~ "/addon-devel/route/wpt[" ~ i ~ "]/distance-m");
             if (distance == nil) {
                 break;
@@ -73,8 +73,8 @@ var RouteDialog = {
 
             if (!isEnd) {
                 if (distance > 0.0) {
-                    totalDistance = totalDistance + distance;
-                    totalAlt = totalAlt + altChange;
+                    totalDistance += distance;
+                    totalAlt += altChange;
                 }
                 else {
                     isEnd = 1;
diff --git a/nasal/flight-plan.nas b/nasal/flight-plan.nas
index 4a70fe5..85b4d5e 100644
--- a/nasal/flight-plan.nas
+++ b/nasal/flight-plan.nas
@@ -17,6 +17,7 @@ var FlightPlan = {
     # Constants
     #
     FILENAME_FLIGHTPLAN: "aerotown-addon-flightplan.xml",
+    MAX_RUNWAY_DISTANCE: 100, # meters
 
     #
     # Constructor
@@ -66,7 +67,7 @@ var FlightPlan = {
 
         var rwyResult = me.findRunway(airport, gliderCoord);
 
-        if (rwyResult.distance > 100) {
+        if (rwyResult.distance > FlightPlan.MAX_RUNWAY_DISTANCE) {
             # The runway is too far away, we assume a bush start
             return {
                 "type"    : "bush",
@@ -181,7 +182,7 @@ var FlightPlan = {
             setprop(me.addonNodePath ~ "/addon-devel/route/wpt[" ~ index ~ "]/distance-m",        wpt.dist);
             setprop(me.addonNodePath ~ "/addon-devel/route/wpt[" ~ index ~ "]/alt-change-agl-ft", wpt.altChange);
 
-            index = index + 1;
+            index += 1;
         }
 
         me.routeDialog.calculateAltChangeAndTotals();
@@ -252,7 +253,7 @@ var FlightPlan = {
             var hdgChange = wptNode.getChild("heading-change").getValue();
             var altChange = aircraft.getAltChange(dist);
 
-            speedInc = speedInc + ((dist / Aircraft.DISTANCE_DETERMINANT) * 0.025);
+            speedInc += ((dist / Aircraft.DISTANCE_DETERMINANT) * 0.025);
             var ktas = aircraft.speed * speedInc;
             if (ktas > aircraft.speedLimit) {
                 ktas = aircraft.speedLimit;
@@ -372,13 +373,13 @@ var FlightPlan = {
     ) {
         var coord = nil;
         if (contains(coordOffset, "hdgChange") and contains(coordOffset, "dist")) {
-            me.heading = me.heading + coordOffset.hdgChange;
+            me.heading += coordOffset.hdgChange;
             if (me.heading < 0) {
-                me.heading = 360 + me.heading;
+                me.heading += 360;
             }
 
             if (me.heading > 360) {
-                me.heading = me.heading - 360;
+                me.heading -= 360;
             }
 
             me.coord.apply_course_distance(me.heading, coordOffset.dist);
@@ -394,7 +395,7 @@ var FlightPlan = {
             alt = me.altitude;
         }
         else if (contains(performance, "altChange")) {
-            me.altitude = me.altitude + performance.altChange;
+            me.altitude += performance.altChange;
             alt = me.altitude;
         }
 
@@ -403,6 +404,6 @@ var FlightPlan = {
         name = name == nil ? me.wptCount : name;
         me.flightPlanWriter.write(name, coord, alt, ktas, groundAir, sec);
 
-        me.wptCount = me.wptCount + 1;
+        me.wptCount += 1;
     },
 };
diff --git a/nasal/io/flight-plan-writer.nas b/nasal/io/flight-plan-writer.nas
index 9a6b5b2..7cd61b7 100644
--- a/nasal/io/flight-plan-writer.nas
+++ b/nasal/io/flight-plan-writer.nas
@@ -63,32 +63,32 @@ var FlightPlanWriter = {
                 ~ "            <name>" ~ name ~ "</name>\n";
 
         if (coord != nil) {
-            str = str ~ "            <lat>" ~ coord.lat() ~ "</lat>\n";
-            str = str ~ "            <lon>" ~ coord.lon() ~ "</lon>\n";
-            str = str ~ "            <!--\n"
-                      ~ "                 " ~ coord.lat() ~ "," ~ coord.lon() ~ "\n"
-                      ~ "            -->\n";
+            str ~= "            <lat>" ~ coord.lat() ~ "</lat>\n";
+            str ~= "            <lon>" ~ coord.lon() ~ "</lon>\n";
+            str ~= "            <!--\n"
+                 ~ "                 " ~ coord.lat() ~ "," ~ coord.lon() ~ "\n"
+                 ~ "            -->\n";
         }
 
         if (alt != nil) {
-            # str = str ~ "            <alt>" ~ alt ~ "</alt>\n";
-            str = str ~ "            <crossat>" ~ alt ~ "</crossat>\n";
+            # str ~= "            <alt>" ~ alt ~ "</alt>\n";
+            str ~= "            <crossat>" ~ alt ~ "</crossat>\n";
         }
 
         if (ktas != nil) {
-            str = str ~ "            <ktas>" ~ ktas ~ "</ktas>\n";
+            str ~= "            <ktas>" ~ ktas ~ "</ktas>\n";
         }
 
         if (groundAir != nil) {
             var onGround = groundAir == "ground" ? "true" : "false";
-            str = str ~ "            <on-ground>" ~ onGround ~ "</on-ground>\n";
+            str ~= "            <on-ground>" ~ onGround ~ "</on-ground>\n";
         }
 
         if (sec != nil) {
-            str = str ~ "            <time-sec>" ~ sec ~ "</time-sec>\n";
+            str ~= "            <time-sec>" ~ sec ~ "</time-sec>\n";
         }
 
-        str = str ~ "        </wpt>\n";
+        str ~= "        </wpt>\n";
 
         io.write(me.fpFileHandler, str);
     },