Detect hangars in IsDepotTypeTile.

diff --git a/src/depot_map.h b/src/depot_map.h
index e559948..4dd6e7a 100644
--- a/src/depot_map.h
+++ b/src/depot_map.h
@@ -29,6 +29,9 @@ static inline bool IsDepotTypeTile(TileIndex tile, TransportType type)
 
 		case TRANSPORT_WATER:
 			return IsShipDepotTile(tile);
+
+		case TRANSPORT_AIR:
+			return IsHangarTile(tile);
 	}
 }