diff --git a/dump1090.c b/dump1090.c
index 7fa5327a3..3f032c8a2 100644
--- a/dump1090.c
+++ b/dump1090.c
@@ -2154,9 +2154,9 @@ char *aircraftsToJson(int *len) {
             l = snprintf(p,buflen,
                 "{\"hex\":\"%s\", \"flight\":\"%s\", \"lat\":%f, "
                 "\"lon\":%f, \"altitude\":%d, \"track\":%d, "
-                "\"speed\":%d},\n",
-                a->hexaddr, a->flight, a->lat, a->lon, a->altitude, a->track,
-                a->speed);
+                "\"speed\":%d, \"metric\":%d},\n",
+                a->hexaddr, a->flight, a->lat, a->lon, altitude, a->track,
+                speed, Modes.metric);
             p += l; buflen -= l;
             /* Resize if needed. */
             if (buflen < 256) {
diff --git a/gmap.html b/gmap.html
index b39a30a22..229cf6559 100644
--- a/gmap.html
+++ b/gmap.html
@@ -90,8 +90,14 @@
         if (p.flight.length) {
             html += '<b>'+p.flight+'</b><br>';
         }
-        html += 'Altitude: '+p.altitude+' feet<br>';
-        html += 'Speed: '+p.speed+' knots<br>';
+        if (p.metric) {
+            html += 'Altitude: '+p.altitude+' meters<br>';
+            html += 'Speed: '+p.speed+' km/h<br>';
+        }
+        else {
+            html += 'Altitude: '+p.altitude+' feet<br>';
+            html += 'Speed: '+p.speed+' knots<br>';
+        }
         html += 'Coordinates: '+p.lat+', '+p.lon+'<br>';
         i.innerHTML = html;
     }
@@ -118,6 +124,7 @@
                     myplane.lon = plane.lon;
                     myplane.track = plane.track;
                     myplane.flight = plane.flight;
+                    myplane.metric = plane.metric;
                     if (myplane.hex == Selected)
                         refreshSelectedInfo();
                 } else {