diff --git a/src/aircraft.h b/src/aircraft.h
index a7d7761a1b..cc9dd8641b 100644
--- a/src/aircraft.h
+++ b/src/aircraft.h
@@ -91,6 +91,7 @@ struct Aircraft : public SpecializedVehicle<Aircraft, VEH_AIRCRAFT> {
 	SpriteID GetImage(Direction direction) const;
 	int GetDisplaySpeed() const    { return this->cur_speed; }
 	int GetDisplayMaxSpeed() const { return this->max_speed; }
+	int GetSpeedOldUnits() const   { return this->max_speed * 10 / 128; }
 	Money GetRunningCost() const;
 	bool IsInDepot() const { return (this->vehstatus & VS_HIDDEN) != 0 && IsHangarTile(this->tile); }
 	bool Tick();
diff --git a/src/economy.cpp b/src/economy.cpp
index f0530c3dac..810e997011 100644
--- a/src/economy.cpp
+++ b/src/economy.cpp
@@ -1231,7 +1231,7 @@ static void LoadUnloadVehicle(Vehicle *v, int *cargo_left)
 			case VEH_TRAIN:    t = Train::From(u)->tcache.cached_max_speed; break;
 			case VEH_ROAD:     t = u->max_speed / 2;        break;
 			case VEH_SHIP:     t = u->max_speed;            break;
-			case VEH_AIRCRAFT: t = u->max_speed * 10 / 128; break; // convert to old units
+			case VEH_AIRCRAFT: t = Aircraft::From(u)->GetSpeedOldUnits(); break; // Convert to old units.
 			default: NOT_REACHED();
 		}
 
diff --git a/src/newgrf_engine.cpp b/src/newgrf_engine.cpp
index 33479cabd8..1d683430c6 100644
--- a/src/newgrf_engine.cpp
+++ b/src/newgrf_engine.cpp
@@ -715,8 +715,20 @@ static uint32 VehicleGetVariable(const ResolverObject *object, byte variable, by
 		case 0x17: return v->tick_counter;
 		case 0x18:
 		case 0x19: {
-			uint max_speed = v->type == VEH_TRAIN ? Train::From(v)->tcache.cached_max_speed : v->max_speed;
-			if (v->type == VEH_AIRCRAFT) max_speed = max_speed * 10 / 128;
+			uint max_speed;
+			switch (v->type) {
+				case VEH_TRAIN:
+					max_speed = Train::From(v)->tcache.cached_max_speed;
+					break;
+
+				case VEH_AIRCRAFT:
+					max_speed = Aircraft::From(v)->GetSpeedOldUnits(); // Convert to old units.
+					break;
+
+				default:
+					max_speed = v->max_speed;
+					break;
+			}
 			return (variable - 0x80) == 0x18 ? max_speed : GB(max_speed, 8, 8);
 		}
 		case 0x1A: return v->x_pos;