(svn r8428) -Codechange: Add proper names to aircraft subtypes instead of magic numbers and add a function IsNormalAircraft() which tells us whether the aircraft is in fact some flying device or a rotor/shadow.

11 files changed, 74 insertions, 50 deletions

diff --git a/src/ai/default/default.cpp b/src/ai/default/default.cpp
index 7316b5648..ed805fb43 100644
--- a/src/ai/default/default.cpp
+++ b/src/ai/default/default.cpp
@@ -95,7 +95,7 @@ static void AiStateVehLoop(Player *p)
 
 		if ((v->type == VEH_Train && v->subtype == 0) ||
 				v->type == VEH_Road ||
-				(v->type == VEH_Aircraft && v->subtype <= 2) ||
+				(v->type == VEH_Aircraft && IsNormalAircraft(v)) ||
 				v->type == VEH_Ship) {
 			/* replace engine? */
 			if (v->type == VEH_Train && v->engine_type < 3 &&
diff --git a/src/aircraft.h b/src/aircraft.h
index 4b92d38e3..9a2875f1f 100644
--- a/src/aircraft.h
+++ b/src/aircraft.h
@@ -6,6 +6,28 @@
 #include "station_map.h"
 #include "vehicle.h"
 
+typedef enum AircraftSubTypes {
+	AIR_HELICOPTER = 0,
+	AIR_AIRCRAFT   = 2,
+	AIR_SHADOW     = 4,
+	AIR_ROTOR      = 6
+} AircraftSubType;
+
+
+/** Check if the aircraft type is a normal flying device; eg
+ * not a rotor or a shadow
+ * @param v vehicle to check
+ * @return Returns true if the aircraft is a helicopter/airplane and
+ * false if it is a shadow or a rotor) */
+static inline bool IsNormalAircraft(const Vehicle *v)
+{
+	assert(v->type == VEH_Aircraft);
+	/* To be fully correct the commented out functionality is the proper one,
+	 * but since value can only be 0 or 2, it is sufficient to only check <= 2
+	 * return (v->subtype == AIR_HELICOPTER) || (v->subtype == AIR_AIRCRAFT); */
+	return v->subtype <= AIR_AIRCRAFT;
+}
+
 
 static inline bool IsAircraftInHangar(const Vehicle* v)
 {
diff --git a/src/aircraft_cmd.cpp b/src/aircraft_cmd.cpp
index 9263c937c..35902a2e6 100644
--- a/src/aircraft_cmd.cpp
+++ b/src/aircraft_cmd.cpp
@@ -17,6 +17,7 @@
 #include "news.h"
 #include "sound.h"
 #include "player.h"
+#include "aircraft.h"
 #include "airport.h"
 #include "vehicle_gui.h"
 #include "table/sprites.h"
@@ -129,7 +130,7 @@ SpriteID GetRotorImage(const Vehicle *v)
 {
 	const Vehicle *w;
 
-	assert((v->subtype & 1) == 0);
+	assert(v->subtype == AIR_HELICOPTER);
 
 	w = v->next->next;
 	if (is_custom_sprite(v->spritenum)) {
@@ -206,11 +207,10 @@ uint16 AircraftDefaultCargoCapacity(CargoID cid, EngineID engine_type)
 int32 CmdBuildAircraft(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
 	int32 value;
-	Vehicle *vl[3], *v, *u, *w;
+	Vehicle *vl[3];
 	UnitID unit_num;
 	const AircraftVehicleInfo *avi;
 	const AirportFTAClass* ap;
-	Engine *e;
 
 	if (!IsEngineBuildable(p1, VEH_Aircraft, _current_player)) return_cmd_error(STR_ENGINE_NOT_BUILDABLE);
 
@@ -231,7 +231,8 @@ int32 CmdBuildAircraft(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 		return CMD_ERROR;
 	}
 
-	// allocate 2 or 3 vehicle structs, depending on type
+	/* Allocate 2 or 3 vehicle structs, depending on type
+	 * vl[0] = aircraft, vl[1] = shadow, [vl[2] = rotor] */
 	if (!AllocateVehicles(vl, avi->subtype & AIR_CTOL ? 2 : 3) ||
 			IsOrderPoolFull()) {
 		return_cmd_error(STR_00E1_TOO_MANY_VEHICLES_IN_GAME);
@@ -246,8 +247,8 @@ int32 CmdBuildAircraft(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 		uint x;
 		uint y;
 
-		v = vl[0];
-		u = vl[1];
+		Vehicle *v = vl[0]; // aircraft
+		Vehicle *u = vl[1]; // shadow
 
 		v->unitnumber = unit_num;
 		v->type = u->type = VEH_Aircraft;
@@ -302,10 +303,10 @@ int32 CmdBuildAircraft(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 		v->acceleration = avi->acceleration;
 		v->engine_type = p1;
 
-		v->subtype = (avi->subtype & AIR_CTOL ? 2 : 0);
+		v->subtype = (avi->subtype & AIR_CTOL ? AIR_AIRCRAFT : AIR_HELICOPTER);
 		v->value = value;
 
-		u->subtype = 4;
+		u->subtype = AIR_SHADOW;
 
 		/* Danger, Will Robinson!
 		 * If the aircraft is refittable, but cannot be refitted to
@@ -333,7 +334,7 @@ int32 CmdBuildAircraft(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 			u->cargo_cap = 0;
 		}
 
-		e = GetEngine(p1);
+		const Engine *e = GetEngine(p1);
 		v->reliability = e->reliability;
 		v->reliability_spd_dec = e->reliability_spd_dec;
 		v->max_age = e->lifelength * 366;
@@ -381,8 +382,8 @@ int32 CmdBuildAircraft(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 		VehiclePositionChanged(u);
 
 		// Aircraft with 3 vehicles (chopper)?
-		if (v->subtype == 0) {
-			w = vl[2];
+		if (v->subtype == AIR_HELICOPTER) {
+			Vehicle *w = vl[2];
 
 			u->next = w;
 
@@ -397,7 +398,7 @@ int32 CmdBuildAircraft(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 			w->z_height = 1;
 			w->vehstatus = VS_HIDDEN | VS_UNCLICKABLE;
 			w->spritenum = 0xFF;
-			w->subtype = 6;
+			w->subtype = AIR_ROTOR;
 			w->cur_image = SPR_ROTOR_STOPPED;
 			w->random_bits = VehicleRandomBits();
 			/* Use rotor's air.state to store the rotor animation frame */
@@ -700,7 +701,7 @@ void OnNewDay_Aircraft(Vehicle *v)
 {
 	int32 cost;
 
-	if (v->subtype > 2) return;
+	if (!IsNormalAircraft(v)) return;
 
 	if ((++v->day_counter & 7) == 0) DecreaseVehicleValue(v);
 
@@ -728,7 +729,7 @@ void AircraftYearlyLoop(void)
 	Vehicle *v;
 
 	FOR_ALL_VEHICLES(v) {
-		if (v->type == VEH_Aircraft && v->subtype <= 2) {
+		if (v->type == VEH_Aircraft && IsNormalAircraft(v)) {
 			v->profit_last_year = v->profit_this_year;
 			v->profit_this_year = 0;
 			InvalidateWindow(WC_VEHICLE_DETAILS, v->index);
@@ -807,7 +808,7 @@ static void SetAircraftPosition(Vehicle *v, int x, int y, int z)
 	v->z_pos = z;
 
 	v->cur_image = GetAircraftImage(v, v->direction);
-	if (v->subtype == 0) v->next->next->cur_image = GetRotorImage(v);
+	if (v->subtype == AIR_HELICOPTER) v->next->next->cur_image = GetRotorImage(v);
 
 	BeginVehicleMove(v);
 	VehiclePositionChanged(v);
@@ -1250,9 +1251,7 @@ static void ProcessAircraftOrder(Vehicle *v)
 static void MarkAircraftDirty(Vehicle *v)
 {
 		v->cur_image = GetAircraftImage(v, v->direction);
-		if (v->subtype == 0) {
-			v->next->next->cur_image = GetRotorImage(v);
-		}
+		if (v->subtype == AIR_HELICOPTER) v->next->next->cur_image = GetRotorImage(v);
 		MarkAllViewportsDirty(v->left_coord, v->top_coord, v->right_coord + 1, v->bottom_coord + 1);
 }
 
@@ -1488,14 +1487,14 @@ static void AircraftEventHandler_InHangar(Vehicle *v, const AirportFTAClass *apc
 	if (v->current_order.dest == v->u.air.targetairport) {
 		// FindFreeTerminal:
 		// 1. Find a free terminal, 2. Occupy it, 3. Set the vehicle's state to that terminal
-		if (v->subtype != 0) {
-			if (!AirportFindFreeTerminal(v, apc)) return; // airplane
-		} else {
+		if (v->subtype == AIR_HELICOPTER) {
 			if (!AirportFindFreeHelipad(v, apc)) return; // helicopter
+		} else {
+			if (!AirportFindFreeTerminal(v, apc)) return; // airplane
 		}
 	} else { // Else prepare for launch.
 		// airplane goto state takeoff, helicopter to helitakeoff
-		v->u.air.state = (v->subtype != 0) ? TAKEOFF : HELITAKEOFF;
+		v->u.air.state = (v->subtype == AIR_HELICOPTER) ? HELITAKEOFF : TAKEOFF;
 	}
 	AircraftLeaveHangar(v);
 	AirportMove(v, apc);
@@ -1510,7 +1509,7 @@ static void AircraftEventHandler_AtTerminal(Vehicle *v, const AirportFTAClass *a
 		// on an airport with helipads, a helicopter will always land there
 		// and get serviced at the same time - patch setting
 		if (_patches.serviceathelipad) {
-			if (v->subtype == 0 && apc->helipads != NULL) {
+			if (v->subtype == AIR_HELICOPTER && apc->helipads != NULL) {
 				// an exerpt of ServiceAircraft, without the invisibility stuff
 				v->date_of_last_service = _date;
 				v->breakdowns_since_last_service = 0;
@@ -1532,13 +1531,13 @@ static void AircraftEventHandler_AtTerminal(Vehicle *v, const AirportFTAClass *a
 	switch (v->current_order.type) {
 		case OT_GOTO_STATION: // ready to fly to another airport
 			// airplane goto state takeoff, helicopter to helitakeoff
-			v->u.air.state = (v->subtype != 0) ? TAKEOFF : HELITAKEOFF;
+			v->u.air.state = (v->subtype == AIR_HELICOPTER) ? HELITAKEOFF : TAKEOFF;
 			break;
 		case OT_GOTO_DEPOT:   // visit hangar for serivicing, sale, etc.
 			if (v->current_order.dest == v->u.air.targetairport) {
 				v->u.air.state = HANGAR;
 			} else {
-				v->u.air.state = (v->subtype != 0) ? TAKEOFF : HELITAKEOFF;
+				v->u.air.state = (v->subtype == AIR_HELICOPTER) ? HELITAKEOFF : TAKEOFF;
 			}
 			break;
 		default:  // orders have been deleted (no orders), goto depot and don't bother us
@@ -1612,7 +1611,7 @@ static void AircraftEventHandler_Flying(Vehicle *v, const AirportFTAClass *apc)
 		// {32,FLYING,NOTHING_block,37}, {32,LANDING,N,33}, {32,HELILANDING,N,41},
 		// if it is an airplane, look for LANDING, for helicopter HELILANDING
 		// it is possible to choose from multiple landing runways, so loop until a free one is found
-		landingtype = (v->subtype != 0) ? LANDING : HELILANDING;
+		landingtype = (v->subtype == AIR_HELICOPTER) ? HELILANDING : LANDING;
 		current = apc->layout[v->u.air.pos].next;
 		while (current != NULL) {
 			if (current->heading == landingtype) {
@@ -2024,9 +2023,9 @@ void Aircraft_Tick(Vehicle *v)
 {
 	int i;
 
-	if (v->subtype > 2) return;
+	if (!IsNormalAircraft(v)) return;
 
-	if (v->subtype == 0) HelicopterTickHandler(v);
+	if (v->subtype == AIR_HELICOPTER) HelicopterTickHandler(v);
 
 	AgeAircraftCargo(v);
 
@@ -2063,7 +2062,7 @@ void UpdateOldAircraft(void)
 	FOR_ALL_VEHICLES(v_oldstyle) {
 	// airplane has another vehicle with subtype 4 (shadow), helicopter also has 3 (rotor)
 	// skip those
-		if (v_oldstyle->type == VEH_Aircraft && v_oldstyle->subtype <= 2) {
+		if (v_oldstyle->type == VEH_Aircraft && IsNormalAircraft(v_oldstyle)) {
 			// airplane in terminal stopped doesn't hurt anyone, so goto next
 			if (v_oldstyle->vehstatus & VS_STOPPED && v_oldstyle->u.air.state == 0) {
 				v_oldstyle->u.air.state = HANGAR;
@@ -2078,7 +2077,7 @@ void UpdateOldAircraft(void)
 			v_oldstyle->tile = 0; // aircraft in air is tile=0
 
 			// correct speed of helicopter-rotors
-			if (v_oldstyle->subtype == 0) v_oldstyle->next->next->cur_speed = 32;
+			if (v_oldstyle->subtype == AIR_HELICOPTER) v_oldstyle->next->next->cur_speed = 32;
 
 			// set new position x,y,z
 			SetAircraftPosition(v_oldstyle, gp.x, gp.y, GetAircraftFlyingAltitude(v_oldstyle));
@@ -2095,7 +2094,7 @@ void UpdateAirplanesOnNewStation(Station *st)
 	// only 1 station is updated per function call, so it is enough to get entry_point once
 	const AirportFTAClass *ap = GetAirport(st->airport_type);
 	FOR_ALL_VEHICLES(v) {
-		if (v->type == VEH_Aircraft && v->subtype <= 2) {
+		if (v->type == VEH_Aircraft && IsNormalAircraft(v)) {
 			if (v->u.air.targetairport == st->index) { // if heading to this airport
 				/* update position of airplane. If plane is not flying, landing, or taking off
 				 *you cannot delete airport, so it doesn't matter
@@ -2110,7 +2109,7 @@ void UpdateAirplanesOnNewStation(Station *st)
 					SetAircraftPosition(v, gp.x, gp.y, GetAircraftFlyingAltitude(v));
 				} else {
 					assert(v->u.air.state == ENDTAKEOFF || v->u.air.state == HELITAKEOFF);
-					takeofftype = (v->subtype == 0) ? HELITAKEOFF : ENDTAKEOFF;
+					takeofftype = (v->subtype == AIR_HELICOPTER) ? HELITAKEOFF : ENDTAKEOFF;
 					// search in airportdata for that heading
 					// easiest to do, since this doesn't happen a lot
 					for (cnt = 0; cnt < ap->nofelements; cnt++) {
diff --git a/src/aircraft_gui.cpp b/src/aircraft_gui.cpp
index b5b2f95e3..ef641ca7c 100644
--- a/src/aircraft_gui.cpp
+++ b/src/aircraft_gui.cpp
@@ -24,7 +24,7 @@ void DrawAircraftImage(const Vehicle *v, int x, int y, VehicleID selection)
 {
 	SpriteID pal = (v->vehstatus & VS_CRASHED) ? PALETTE_CRASH : GetVehiclePalette(v);
 	DrawSprite(GetAircraftImage(v, DIR_W), pal, x + 25, y + 10);
-	if (v->subtype == 0) {
+	if (v->subtype == AIR_HELICOPTER) {
 		SpriteID rotor_sprite = GetCustomRotorSprite(v, true);
 		if (rotor_sprite == 0) rotor_sprite = SPR_ROTOR_STOPPED;
 		DrawSprite(rotor_sprite, PAL_NONE, x + 25, y + 5);
@@ -114,7 +114,7 @@ static void AircraftDetailsWndProc(Window *w, WindowEvent *e)
 			int y = 57;
 
 			do {
-				if (v->subtype <= 2) {
+				if (IsNormalAircraft(v)) {
 					SetDParam(0, GetCustomEngineName(v->engine_type));
 					SetDParam(1, v->build_year);
 					SetDParam(2, v->value);
diff --git a/src/economy.cpp b/src/economy.cpp
index a1a63ee1e..b422b8a53 100644
--- a/src/economy.cpp
+++ b/src/economy.cpp
@@ -27,6 +27,7 @@
 #include "vehicle_gui.h"
 #include "ai/ai.h"
 #include "train.h"
+#include "aircraft.h"
 #include "newgrf_engine.h"
 #include "newgrf_sound.h"
 #include "newgrf_callbacks.h"
@@ -76,7 +77,7 @@ int64 CalculateCompanyValue(const Player* p)
 
 			if (v->type == VEH_Train ||
 					v->type == VEH_Road ||
-					(v->type == VEH_Aircraft && v->subtype<=2) ||
+					(v->type == VEH_Aircraft && IsNormalAircraft(v)) ||
 					v->type == VEH_Ship) {
 				value += v->value * 3 >> 1;
 			}
@@ -108,7 +109,7 @@ int UpdateCompanyRatingAndValue(Player *p, bool update)
 			if (v->owner != owner) continue;
 			if ((v->type == VEH_Train && IsFrontEngine(v)) ||
 					 v->type == VEH_Road ||
-					(v->type == VEH_Aircraft && v->subtype <= 2) ||
+					(v->type == VEH_Aircraft && IsNormalAircraft(v)) ||
 					 v->type == VEH_Ship) {
 				num++;
 				if (v->age > 730) {
@@ -299,7 +300,7 @@ void ChangeOwnershipOfPlayerItems(PlayerID old_player, PlayerID new_player)
 					case VEH_Train:    if (IsFrontEngine(v)) num_train++; break;
 					case VEH_Road:     num_road++; break;
 					case VEH_Ship:     num_ship++; break;
-					case VEH_Aircraft: if (v->subtype <= 2) num_aircraft++; break;
+					case VEH_Aircraft: if (IsNormalAircraft(v)) num_aircraft++; break;
 					default: break;
 				}
 			}
@@ -319,7 +320,7 @@ void ChangeOwnershipOfPlayerItems(PlayerID old_player, PlayerID new_player)
 						case VEH_Train:    if (IsFrontEngine(v)) v->unitnumber = ++num_train; break;
 						case VEH_Road:     v->unitnumber = ++num_road; break;
 						case VEH_Ship:     v->unitnumber = ++num_ship; break;
-						case VEH_Aircraft: if (v->subtype <= 2) v->unitnumber = ++num_aircraft; break;
+						case VEH_Aircraft: if (IsNormalAircraft(v)) v->unitnumber = ++num_aircraft; break;
 					}
 				}
 			}
diff --git a/src/engine.cpp b/src/engine.cpp
index 10a35b9a0..ec4c27ec2 100644
--- a/src/engine.cpp
+++ b/src/engine.cpp
@@ -14,6 +14,7 @@
 #include "saveload.h"
 #include "variables.h"
 #include "train.h"
+#include "aircraft.h"
 #include "newgrf_cargo.h"
 #include "date.h"
 #include "table/engines.h"
@@ -306,7 +307,7 @@ static void NewVehicleAvailable(Engine *e)
 
 			FOR_ALL_VEHICLES(v) {
 				if (v->type == VEH_Train || v->type == VEH_Road || v->type == VEH_Ship ||
-						(v->type == VEH_Aircraft && v->subtype <= 2)) {
+						(v->type == VEH_Aircraft && IsNormalAircraft(v))) {
 					if (v->owner == p->index && v->engine_type == index) {
 						/* The user did prove me wrong, so restore old value */
 						p->block_preview = block_preview;
diff --git a/src/engine.h b/src/engine.h
index 05ffb33a7..3b70256a2 100644
--- a/src/engine.h
+++ b/src/engine.h
@@ -45,7 +45,7 @@ typedef struct ShipVehicleInfo {
 	bool refittable;
 } ShipVehicleInfo;
 
-// Aircraft subtypes
+/* AircraftVehicleInfo subtypes */
 enum {
 	AIR_CTOL = 1, // Conventional Take Off and Landing, i.e. planes
 	AIR_FAST = 2
diff --git a/src/network/network_server.cpp b/src/network/network_server.cpp
index 612a9edef..f69340afd 100644
--- a/src/network/network_server.cpp
+++ b/src/network/network_server.cpp
@@ -10,6 +10,7 @@
 #include "network_data.h"
 #include "core/tcp.h"
 #include "../train.h"
+#include "../aircraft.h"
 #include "../date.h"
 #include "table/strings.h"
 #include "../functions.h"
@@ -1255,7 +1256,7 @@ void NetworkPopulateCompanyInfo(void)
 				break;
 
 			case VEH_Aircraft:
-				if (v->subtype <= 2) _network_player_info[v->owner].num_vehicle[3]++;
+				if (IsNormalAircraft(v)) _network_player_info[v->owner].num_vehicle[3]++;
 				break;
 
 			case VEH_Ship:
diff --git a/src/player_gui.cpp b/src/player_gui.cpp
index e51a6d4f9..94367e1ad 100644
--- a/src/player_gui.cpp
+++ b/src/player_gui.cpp
@@ -16,6 +16,7 @@
 #include "network/network.h"
 #include "variables.h"
 #include "train.h"
+#include "aircraft.h"
 #include "date.h"
 #include "newgrf.h"
 #include "network/network_data.h"
@@ -607,7 +608,7 @@ static void DrawPlayerVehiclesAmount(PlayerID player)
 			switch (v->type) {
 				case VEH_Train:    if (IsFrontEngine(v)) train++; break;
 				case VEH_Road:     road++; break;
-				case VEH_Aircraft: if (v->subtype <= 2) air++; break;
+				case VEH_Aircraft: if (IsNormalAircraft(v)) air++; break;
 				case VEH_Ship:     ship++; break;
 				default: break;
 			}
diff --git a/src/vehicle.cpp b/src/vehicle.cpp
index 41be1ea75..b28852d96 100644
--- a/src/vehicle.cpp
+++ b/src/vehicle.cpp
@@ -232,7 +232,7 @@ void AfterLoadVehicles(void)
 			case VEH_Road: v->cur_image = GetRoadVehImage(v, v->direction); break;
 			case VEH_Ship: v->cur_image = GetShipImage(v, v->direction); break;
 			case VEH_Aircraft:
-				if (v->subtype == 0 || v->subtype == 2) {
+				if (IsNormalAircraft(v)) {
 					v->cur_image = GetAircraftImage(v, v->direction);
 					if (v->next != NULL) v->next->cur_image = v->cur_image;
 				}
@@ -537,7 +537,7 @@ uint CountVehiclesInChain(const Vehicle* v)
 bool IsEngineCountable(const Vehicle *v)
 {
 	switch (v->type) {
-		case VEH_Aircraft: return (v->subtype <= 2); // don't count plane shadows and helicopter rotors
+		case VEH_Aircraft: return IsNormalAircraft(v); // don't count plane shadows and helicopter rotors
 		case VEH_Train:
 			return !IsArticulatedPart(v) && // tenders and other articulated parts
 			(!IsMultiheaded(v) || IsTrainEngine(v)); // rear parts of multiheaded engines
@@ -651,7 +651,7 @@ void CallVehicleTicks(void)
 			case VEH_Aircraft:
 			case VEH_Ship:
 				if (v->type == VEH_Train && IsTrainWagon(v)) continue;
-				if (v->type == VEH_Aircraft && v->subtype > 0) continue;
+				if (v->type == VEH_Aircraft && v->subtype != AIR_HELICOPTER) continue;
 
 				v->motion_counter += (v->direction & 1) ? (v->cur_speed * 3) / 4 : v->cur_speed;
 				/* Play a running sound if the motion counter passes 256 (Do we not skip sounds?) */
@@ -2334,8 +2334,7 @@ void BuildDepotVehicleList(byte type, TileIndex tile, Vehicle ***engine_list, ui
 		case VEH_Aircraft:
 			FOR_ALL_VEHICLES(v) {
 				if (v->tile == tile &&
-						v->type == VEH_Aircraft &&
-						v->subtype <= 2 &&
+						v->type == VEH_Aircraft && IsNormalAircraft(v) &&
 						v->vehstatus & VS_HIDDEN) {
 					if (*engine_count == *engine_list_length) ExtendVehicleListSize((const Vehicle***)engine_list, engine_list_length, 25);
 					(*engine_list)[(*engine_count)++] = v;
@@ -2362,7 +2361,7 @@ void BuildDepotVehicleList(byte type, TileIndex tile, Vehicle ***engine_list, ui
 */
 uint GenerateVehicleSortList(const Vehicle ***sort_list, uint16 *length_of_array, byte type, PlayerID owner, uint32 index, uint16 window_type)
 {
-	const uint subtype = (type != VEH_Aircraft) ? Train_Front : 2;
+	const byte subtype = (type != VEH_Aircraft) ? (byte)Train_Front : (byte)AIR_AIRCRAFT;
 	uint n = 0;
 	const Vehicle *v;
 
diff --git a/src/vehicle.h b/src/vehicle.h
index dc994b832..2b7773ced 100644
--- a/src/vehicle.h
+++ b/src/vehicle.h
@@ -144,7 +144,7 @@ typedef struct VehicleShip {
 
 struct Vehicle {
 	byte type;               // type, ie roadven,train,ship,aircraft,special
-	byte subtype;            // subtype (Filled with values from EffectVehicles or TrainSubTypes)
+	byte subtype;            // subtype (Filled with values from EffectVehicles/TrainSubTypes/AircraftSubTypes)
 
 	VehicleID index;         // NOSAVE: Index in vehicle array