diff --git a/src/aircraft.h b/src/aircraft.h
--- a/src/aircraft.h
+++ b/src/aircraft.h
@@ -21,20 +21,6 @@ enum 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;
-}
-
 /**
  * Calculates cargo capacity based on an aircraft's passenger
  * and mail capacities.
@@ -108,7 +94,7 @@ struct Aircraft : public SpecializedVehi
 	void MarkDirty();
 	void UpdateDeltaXY(Direction direction);
 	ExpensesType GetExpenseType(bool income) const { return income ? EXPENSES_AIRCRAFT_INC : EXPENSES_AIRCRAFT_RUN; }
-	bool IsPrimaryVehicle() const { return IsNormalAircraft(this); }
+	bool IsPrimaryVehicle() const { return this->IsNormalAircraft(); }
 	SpriteID GetImage(Direction direction) const;
 	int GetDisplaySpeed() const { return this->cur_speed; }
 	int GetDisplayMaxSpeed() const { return this->max_speed; }
@@ -118,6 +104,20 @@ struct Aircraft : public SpecializedVehi
 	void OnNewDay();
 	TileIndex GetOrderStationLocation(StationID station);
 	bool FindClosestDepot(TileIndex *location, DestinationID *destination, bool *reverse);
+
+	/**
+	 * Check if the aircraft type is a normal flying device; eg
+	 * not a rotor or a shadow
+	 * @return Returns true if the aircraft is a helicopter/airplane and
+	 * false if it is a shadow or a rotor
+	 */
+	FORCEINLINE bool IsNormalAircraft() const
+	{
+		/* 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 (this->subtype == AIR_HELICOPTER) || (this->subtype == AIR_AIRCRAFT); */
+		return this->subtype <= AIR_AIRCRAFT;
+	}
 };
 
 #define FOR_ALL_AIRCRAFT(var) FOR_ALL_VEHICLES_OF_TYPE(Aircraft, var)
diff --git a/src/aircraft_cmd.cpp b/src/aircraft_cmd.cpp
--- a/src/aircraft_cmd.cpp
+++ b/src/aircraft_cmd.cpp
@@ -613,7 +613,7 @@ Money Aircraft::GetRunningCost() const
 
 void Aircraft::OnNewDay()
 {
-	if (!IsNormalAircraft(this)) return;
+	if (!this->IsNormalAircraft()) return;
 
 	if ((++this->day_counter & 7) == 0) DecreaseVehicleValue(this);
 
@@ -2029,7 +2029,7 @@ static bool AircraftEventHandler(Aircraf
 
 bool Aircraft::Tick()
 {
-	if (!IsNormalAircraft(this)) return true;
+	if (!this->IsNormalAircraft()) return true;
 
 	if (!(this->vehstatus & VS_STOPPED)) this->running_ticks++;
 
@@ -2074,7 +2074,7 @@ void UpdateAirplanesOnNewStation(const S
 
 	Aircraft *v;
 	FOR_ALL_AIRCRAFT(v) {
-		if (IsNormalAircraft(v)) {
+		if (v->IsNormalAircraft()) {
 			if (v->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 */
diff --git a/src/aircraft_gui.cpp b/src/aircraft_gui.cpp
--- a/src/aircraft_gui.cpp
+++ b/src/aircraft_gui.cpp
@@ -22,13 +22,13 @@
  * @param right The right most coordinate to draw
  * @param y     The y coordinate
  */
-void DrawAircraftDetails(const Vehicle *v, int left, int right, int y)
+void DrawAircraftDetails(const Aircraft *v, int left, int right, int y)
 {
 	int y_offset = (v->Next()->cargo_cap != 0) ? -11 : 0;
 	Money feeder_share = 0;
 
-	for (const Vehicle *u = v ; u != NULL ; u = u->Next()) {
-		if (IsNormalAircraft(u)) {
+	for (const Aircraft *u = v ; u != NULL ; u = u->Next()) {
+		if (u->IsNormalAircraft()) {
 			SetDParam(0, u->engine_type);
 			SetDParam(1, u->build_year);
 			SetDParam(2, u->value);
diff --git a/src/economy.cpp b/src/economy.cpp
--- a/src/economy.cpp
+++ b/src/economy.cpp
@@ -123,7 +123,7 @@ Money CalculateCompanyValue(const Compan
 
 		if (v->type == VEH_TRAIN ||
 				v->type == VEH_ROAD ||
-				(v->type == VEH_AIRCRAFT && IsNormalAircraft(v)) ||
+				(v->type == VEH_AIRCRAFT && Aircraft::From(v)->IsNormalAircraft()) ||
 				v->type == VEH_SHIP) {
 			value += v->value * 3 >> 1;
 		}
@@ -1300,7 +1300,7 @@ static void LoadUnloadVehicle(Vehicle *v
 		byte load_amount = EngInfo(v->engine_type)->load_amount;
 
 		/* The default loadamount for mail is 1/4 of the load amount for passengers */
-		if (v->type == VEH_AIRCRAFT && !IsNormalAircraft(v)) load_amount = (load_amount + 3) / 4;
+		if (v->type == VEH_AIRCRAFT && !Aircraft::From(v)->IsNormalAircraft()) load_amount = (load_amount + 3) / 4;
 
 		if (_settings_game.order.gradual_loading && HasBit(EngInfo(v->engine_type)->callbackmask, CBM_VEHICLE_LOAD_AMOUNT)) {
 			uint16 cb_load_amount = GetVehicleCallback(CBID_VEHICLE_LOAD_AMOUNT, 0, 0, v->engine_type, v);
diff --git a/src/engine.cpp b/src/engine.cpp
--- a/src/engine.cpp
+++ b/src/engine.cpp
@@ -658,7 +658,7 @@ static void NewVehicleAvailable(Engine *
 
 			FOR_ALL_VEHICLES(v) {
 				if (v->type == VEH_TRAIN || v->type == VEH_ROAD || v->type == VEH_SHIP ||
-						(v->type == VEH_AIRCRAFT && IsNormalAircraft(v))) {
+						(v->type == VEH_AIRCRAFT && Aircraft::From(v)->IsNormalAircraft())) {
 					if (v->owner == c->index && v->engine_type == index) {
 						/* The user did prove me wrong, so restore old value */
 						c->block_preview = block_preview;
diff --git a/src/saveload/afterload.cpp b/src/saveload/afterload.cpp
--- a/src/saveload/afterload.cpp
+++ b/src/saveload/afterload.cpp
@@ -1760,7 +1760,7 @@ bool AfterLoadGame()
 		Aircraft *a;
 		FOR_ALL_AIRCRAFT(a) {
 			/* Set engine_type of shadow and rotor */
-			if (!IsNormalAircraft(a)) {
+			if (!a->IsNormalAircraft()) {
 				a->engine_type = a->First()->engine_type;
 			}
 		}
diff --git a/src/saveload/vehicle_sl.cpp b/src/saveload/vehicle_sl.cpp
--- a/src/saveload/vehicle_sl.cpp
+++ b/src/saveload/vehicle_sl.cpp
@@ -164,7 +164,7 @@ void UpdateOldAircraft()
 	FOR_ALL_AIRCRAFT(a) {
 		/* airplane has another vehicle with subtype 4 (shadow), helicopter also has 3 (rotor)
 		 * skip those */
-		if (IsNormalAircraft(a)) {
+		if (a->IsNormalAircraft()) {
 			/* airplane in terminal stopped doesn't hurt anyone, so goto next */
 			if ((a->vehstatus & VS_STOPPED) && a->state == 0) {
 				a->state = HANGAR;
@@ -356,7 +356,7 @@ void AfterLoadVehicles(bool part_of_load
 				break;
 
 			case VEH_AIRCRAFT:
-				if (IsNormalAircraft(v)) {
+				if (Aircraft::From(v)->IsNormalAircraft()) {
 					v->cur_image = v->GetImage(v->direction);
 
 					/* The plane's shadow will have the same image as the plane */
diff --git a/src/station.cpp b/src/station.cpp
--- a/src/station.cpp
+++ b/src/station.cpp
@@ -63,7 +63,7 @@ Station::~Station()
 
 	Aircraft *a;
 	FOR_ALL_AIRCRAFT(a) {
-		if (!IsNormalAircraft(a)) continue;
+		if (!a->IsNormalAircraft()) continue;
 		if (a->targetairport == this->index) a->targetairport = INVALID_STATION;
 	}
 
diff --git a/src/station_cmd.cpp b/src/station_cmd.cpp
--- a/src/station_cmd.cpp
+++ b/src/station_cmd.cpp
@@ -1878,7 +1878,7 @@ static CommandCost RemoveAirport(TileInd
 
 	const Aircraft *a;
 	FOR_ALL_AIRCRAFT(a) {
-		if (!IsNormalAircraft(a)) continue;
+		if (!a->IsNormalAircraft()) continue;
 		if (a->targetairport == st->index && a->state != FLYING) return CMD_ERROR;
 	}
 
diff --git a/src/vehicle.cpp b/src/vehicle.cpp
--- a/src/vehicle.cpp
+++ b/src/vehicle.cpp
@@ -478,7 +478,7 @@ uint CountVehiclesInChain(const Vehicle 
 bool Vehicle::IsEngineCountable() const
 {
 	switch (this->type) {
-		case VEH_AIRCRAFT: return IsNormalAircraft(this); // don't count plane shadows and helicopter rotors
+		case VEH_AIRCRAFT: return Aircraft::From(this)->IsNormalAircraft(); // don't count plane shadows and helicopter rotors
 		case VEH_TRAIN:
 			return !Train::From(this)->IsArticulatedPart() && // tenders and other articulated parts
 					!Train::From(this)->IsRearDualheaded(); // rear parts of multiheaded engines
diff --git a/src/vehicle_gui.cpp b/src/vehicle_gui.cpp
--- a/src/vehicle_gui.cpp
+++ b/src/vehicle_gui.cpp
@@ -19,6 +19,7 @@
 #include "station_base.h"
 #include "roadveh.h"
 #include "train.h"
+#include "aircraft.h"
 #include "depot_base.h"
 #include "group_gui.h"
 #include "strings_func.h"
@@ -1343,7 +1344,7 @@ extern int GetTrainDetailsWndVScroll(Veh
 extern void DrawTrainDetails(const Train *v, int left, int right, int y, int vscroll_pos, uint16 vscroll_cap, TrainDetailsWindowTabs det_tab);
 extern void DrawRoadVehDetails(const Vehicle *v, int left, int right, int y);
 extern void DrawShipDetails(const Vehicle *v, int left, int right, int y);
-extern void DrawAircraftDetails(const Vehicle *v, int left, int right, int y);
+extern void DrawAircraftDetails(const Aircraft *v, int left, int right, int y);
 
 struct VehicleDetailsWindow : Window {
 	TrainDetailsWindowTabs tab;
@@ -1436,7 +1437,7 @@ struct VehicleDetailsWindow : Window {
 			case VEH_TRAIN:    DrawTrainDetails(Train::From(v), left, right, y, vscroll_pos, vscroll_cap, det_tab);  break;
 			case VEH_ROAD:     DrawRoadVehDetails(v, left, right, y);  break;
 			case VEH_SHIP:     DrawShipDetails(v, left, right, y);     break;
-			case VEH_AIRCRAFT: DrawAircraftDetails(v, left, right, y); break;
+			case VEH_AIRCRAFT: DrawAircraftDetails(Aircraft::From(v), left, right, y); break;
 			default: NOT_REACHED();
 		}
 	}