/* Prevent building aircraft types at places which can't handle them */

	if (!CanAircraftUseStation(p1, tile)) return CMD_ERROR;

	/* Allocate 2 or 3 vehicle structs, depending on type

	 * vl[0] = aircraft, vl[1] = shadow, [vl[2] = rotor] */

	Vehicle *vl[3];

	if (!Vehicle::AllocateList(vl, avi->subtype & AIR_CTOL ? 2 : 3)) {

		return_cmd_error(STR_00E1_TOO_MANY_VEHICLES_IN_GAME);

	}

	UnitID unit_num = HasBit(p2, 0) ? 0 : GetFreeUnitNumber(VEH_AIRCRAFT);

		return_cmd_error(STR_00E1_TOO_MANY_VEHICLES_IN_GAME);

	if (flags & DC_EXEC) {

		Vehicle *v = vl[0]; // aircraft

		Vehicle *u = vl[1]; // shadow

		v = new (v) Aircraft();

		u = new (u) Aircraft();

		v->unitnumber = unit_num;

		v->direction = DIR_SE;

		v->owner = u->owner = _current_player;

			if (st->airport_tile + ToTileIndexDiff(apc->airport_depots[i]) == tile) {

				assert(apc->layout[i].heading == HANGAR);

				v->u.air.pos = apc->layout[i].position;

				break;

			}

		}

		v->u.air.state = HANGAR;

		v->u.air.previous_pos = v->u.air.pos;

		v->u.air.targetairport = GetStationIndex(tile);

		v->SetNext(u);

		v->date_of_last_service = _date;

		v->build_year = u->build_year = _cur_year;

		v->cur_image = u->cur_image = 0xEA0;

		v->random_bits = VehicleRandomBits();

		u->random_bits = VehicleRandomBits();

		v->vehicle_flags = 0;

		if (e->flags & ENGINE_EXCLUSIVE_PREVIEW) SetBit(v->vehicle_flags, VF_BUILT_AS_PROTOTYPE);

		v->cargo_subtype = new_subtype;

		InvalidateWindow(WC_VEHICLE_DETAILS, v->index);

		InvalidateWindow(WC_VEHICLE_DEPOT, v->tile);

		InvalidateWindowClassesData(WC_AIRCRAFT_LIST, 0);

	}

	return cost;

}

static void CheckIfAircraftNeedsService(Vehicle *v)

{

	if (v->IsInDepot()) {

		VehicleServiceInDepot(v);

		return;

	}

	const Station *st = GetStation(v->current_order.GetDestination());

	/* only goto depot if the target airport has terminals (eg. it is airport) */

	if (st->IsValid() && st->airport_tile != 0 && st->Airport()->terminals != NULL) {

//		printf("targetairport = %d, st->index = %d\n", v->u.air.targetairport, st->index);

//		v->u.air.targetairport = st->index;

		v->current_order.MakeGoToDepot(st->index, ODTFB_SERVICE);

		InvalidateWindowWidget(WC_VEHICLE_VIEW, v->index, VVW_WIDGET_START_STOP_VEH);

 * @param v The vehicle for which the speed should be obtained

 * @param speed_limit The maximum speed the vehicle may have.

 * @param hard_limit If true, the limit is directly enforced, otherwise the plane is slowed down gradually

 * @return The number of position updates needed within the tick

 */

static int UpdateAircraftSpeed(Vehicle *v, uint speed_limit = SPEED_LIMIT_NONE, bool hard_limit = true)

{

	uint spd = v->acceleration * 16;

	byte t;

	/* Adjust speed limits by plane speed factor to prevent taxiing

	 * and take-off speeds being too low. */

	if (v->u.air.cached_max_speed < speed_limit) {

		if (v->cur_speed < speed_limit) hard_limit = false;

		speed_limit = v->u.air.cached_max_speed;

	}

	speed_limit = min(speed_limit, v->max_speed);

	v->subspeed = (t=v->subspeed) + (byte)spd;

	/* Aircraft's current speed is used twice so that very fast planes are

	 * forced to slow down rapidly in the short distance needed. The magic

	 * value 16384 was determined to give similar results to the old speed/48

	 * method at slower speeds. This also results in less reduction at slow

	 * speeds to that aircraft do not get to taxi speed straight after

	 * touchdown. */

	if (!hard_limit && v->cur_speed > speed_limit) {

	}

	spd = min(v->cur_speed + (spd >> 8) + (v->subspeed < t), speed_limit);

	/* adjust speed for broken vehicles */

	if (v->vehstatus & VS_AIRCRAFT_BROKEN) spd = min(spd, SPEED_LIMIT_BROKEN);

	/* updates statusbar only if speed have changed to save CPU time */

	if (spd != v->cur_speed) {

		v->cur_speed = spd;

			InvalidateWindowWidget(WC_VEHICLE_VIEW, v->index, VVW_WIDGET_START_STOP_VEH);

	}

	/* Adjust distance moved by plane speed setting */

	if (!(v->direction & 1)) spd = spd * 3 / 4;

	spd += v->progress;

	v->progress = (byte)spd;

	return spd >> 8;

}

/**

 * Gets the cruise altitude of an aircraft.

 * The cruise altitude is determined by the velocity of the vehicle

 * and the direction it is moving

	AircraftLeaveHangar(v);

	AirportMove(v, apc);

}

/** At one of the Airport's Terminals */

static void AircraftEventHandler_AtTerminal(Vehicle *v, const AirportFTAClass *apc)

{

	/* if we just arrived, execute EnterTerminal first */

	if (v->u.air.previous_pos != v->u.air.pos) {

		AircraftEventHandler_EnterTerminal(v, apc);

		/* on an airport with helipads, a helicopter will always land there

		 * and get serviced at the same time - patch setting */

			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;

				v->reliability = GetEngine(v->engine_type)->reliability;

				InvalidateWindow(WC_VEHICLE_DETAILS, v->index);

			}

		}

		return;

	}

	if (!v->current_order.IsValid()) return;