diff --git a/simgear/environment/metar.cxx b/simgear/environment/metar.cxx
index 91846d5f..08e72bfb 100644
--- a/simgear/environment/metar.cxx
+++ b/simgear/environment/metar.cxx
@@ -631,11 +631,15 @@ bool SGMetar::scanWind()
 	int dir;
 	if (!strncmp(m, "VRB", 3))
 		m += 3, dir = -1;
+	else if (!strncmp(m, "///", 3))	// direction not measurable
+		m += 3, dir = -1;
 	else if (!scanNumber(&m, &dir, 3))
 		return false;
 
 	int i;
-	if (!scanNumber(&m, &i, 2, 3))
+	if (!strncmp(m, "//", 2))	// speed not measurable
+		m += 2, i = -1;
+	else if (!scanNumber(&m, &i, 2, 3))
 		return false;
 	double speed = i;
 
diff --git a/simgear/environment/test_metar.cxx b/simgear/environment/test_metar.cxx
index f97a3d18..bf5d2cbe 100644
--- a/simgear/environment/test_metar.cxx
+++ b/simgear/environment/test_metar.cxx
@@ -76,12 +76,20 @@ void test_sensor_failure_cloud()
     SG_CHECK_EQUAL_EP2(m1.getPressure_hPa(), 1025, TEST_EPSILON);
 }
 
+void test_sensor_failure_wind()
+{
+    SGMetar m1("2020/10/23 16:55 LIVD 231655Z /////KT 9999 OVC025 10/08 Q1020 RMK OVC VIS MIN 9999 BLU");
+    SG_CHECK_EQUAL(m1.getWindDir(), -1);
+    SG_CHECK_EQUAL_EP2(m1.getWindSpeed_kt(), -1, TEST_EPSILON);
+}
+
 int main(int argc, char* argv[])
 {
     try {
         test_basic();
         test_sensor_failure_weather();
         test_sensor_failure_cloud();
+        test_sensor_failure_wind();
     } catch (sg_exception& e) {
         cerr << "got exception:" << e.getMessage() << endl;
         return -1;