--- a/src/aircraft.h	Tue Mar 06 22:01:59 2007 +0000
+++ b/src/aircraft.h	Tue Mar 06 22:11:58 2007 +0000
@@ -42,6 +42,20 @@
 	return IsAircraftInHangar(v) && v->vehstatus & VS_STOPPED;
 }
 
+/** Checks if an aircraft is buildable at the tile in question
+ * @param engine The engine to test
+ * @param tile The tile where the hangar is
+ * @return true if the aircraft can be build
+ */
+static inline bool IsAircraftBuildableAtStation(EngineID engine, TileIndex tile)
+{
+	const Station *st = GetStationByTile(tile);
+	const AirportFTAClass *apc = st->Airport();
+	const AircraftVehicleInfo *avi = AircraftVehInfo(engine);
+
+	return apc->flags & (avi->subtype & AIR_CTOL ? AirportFTAClass::AIRPLANES : AirportFTAClass::HELICOPTERS);
+}
+
 uint16 AircraftDefaultCargoCapacity(CargoID cid, const AircraftVehicleInfo*);
 
 void CcBuildAircraft(bool success, TileIndex tile, uint32 p1, uint32 p2);

--- a/src/aircraft_cmd.cpp	Tue Mar 06 22:01:59 2007 +0000
+++ b/src/aircraft_cmd.cpp	Tue Mar 06 22:11:58 2007 +0000
@@ -227,7 +227,6 @@
 	}
 }
 
-
 /** Build an aircraft.
  * @param tile tile of depot where aircraft is built
  * @param flags for command
@@ -250,11 +249,7 @@
 	SET_EXPENSES_TYPE(EXPENSES_NEW_VEHICLES);
 
 	/* Prevent building aircraft types at places which can't handle them */
-	const Station* st = GetStationByTile(tile);
-	const AirportFTAClass* apc = st->Airport();
-	if (!(apc->flags & (avi->subtype & AIR_CTOL ? AirportFTAClass::AIRPLANES : AirportFTAClass::HELICOPTERS))) {
-		return CMD_ERROR;
-	}
+	if (!IsAircraftBuildableAtStation(p1, tile)) return CMD_ERROR;
 
 	/* Allocate 2 or 3 vehicle structs, depending on type
 	 * vl[0] = aircraft, vl[1] = shadow, [vl[2] = rotor] */
@@ -367,6 +362,9 @@
 		 * layout for #th position of depot. Since layout must start with a listing
 		 * of all depots, it is simple */
 		for (uint i = 0;; i++) {
+			const Station *st = GetStationByTile(tile);
+			const AirportFTAClass *apc = st->Airport();
+
 			assert(i != apc->nof_depots);
 			if (st->airport_tile + ToTileIndexDiff(apc->airport_depots[i]) == tile) {
 				assert(apc->layout[i].heading == HANGAR);

--- a/src/build_vehicle_gui.cpp	Tue Mar 06 22:01:59 2007 +0000
+++ b/src/build_vehicle_gui.cpp	Tue Mar 06 22:11:58 2007 +0000
@@ -694,26 +694,11 @@
 	 * when planes become obsolete and are removed */
 	sel_id = INVALID_ENGINE;
 	for (eid = AIRCRAFT_ENGINES_INDEX; eid < AIRCRAFT_ENGINES_INDEX + NUM_AIRCRAFT_ENGINES; eid++) {
-		if (IsEngineBuildable(eid, VEH_Aircraft, _local_player)) {
-			const AircraftVehicleInfo *avi = AircraftVehInfo(eid);
-			switch (bv->filter.flags & ~AirportFTAClass::SHORT_STRIP) { // we don't care about the length of the runway here
-				case AirportFTAClass::HELICOPTERS:
-					if (avi->subtype != AIR_HELI) continue;
-					break;
+		if (!IsEngineBuildable(eid, VEH_Aircraft, _local_player)) continue;
+		if (w->window_number != 0 && !IsAircraftBuildableAtStation(eid, w->window_number)) continue;
 
-				case AirportFTAClass::AIRPLANES:
-					if (!(avi->subtype & AIR_CTOL)) continue;
-					break;
-
-				case AirportFTAClass::ALL: break;
-				default:
-					NOT_REACHED();
-			}
-
-			EngList_Add(&bv->eng_list, eid);
-
-			if (eid == bv->sel_engine) sel_id = eid;
-		}
+		EngList_Add(&bv->eng_list, eid);
+		if (eid == bv->sel_engine) sel_id = eid;
 	}
 
 	bv->sel_engine = sel_id;