Index: trunk/data/validator/geometry.mapcss
===================================================================
--- trunk/data/validator/geometry.mapcss	(revision 15150)
+++ trunk/data/validator/geometry.mapcss	(revision 15151)
@@ -385,2 +385,10 @@
   throwWarning: tr("Ferry route is not connected to a ferry terminal or branches.");
 }
+
+/* #10391 - Many misuses of building=hangar instead of building=barn/industrial/warehouse */
+area:closed2[aeroway] ⊉ way[building=hangar][!aeroway] {
+  throwWarning: tr("{0} outside of {1}", "{0.tag}", "aeroway");
+  suggestAlternative: "building=barn";
+  suggestAlternative: "building=industrial";
+  suggestAlternative: "building=warehouse";
+}