// script_airport.hpp
	/**
	 * Checks whether the noise that will be added to the nearest town if an airport would be
	 *  built at this tile is allowed.
	 * @param tile The tile to check.
	 * @param type The AirportType to check.
	 * @return true if and only if the noise level increase added by the airport is allowed.
	 * @note The noise will be added to the town with TownID GetNearestTown(tile, type).
	 */
	static bool ScriptAirport::IsNoiseLevelIncreaseAllowed(TileIndex tile, AirportType type);

// script_airport.cpp
/* static */ bool ScriptAirport::IsNoiseLevelIncreaseAllowed(TileIndex tile, AirportType type)
{
	extern Town *AirportGetNearestTown(const AirportSpec *as, const TileIterator &it, uint &mindist);
	extern uint8 GetAirportNoiseLevelForDistance(const AirportSpec *as, uint distance);

	if (!::IsValidTile(tile)) return false;
	if (!IsAirportInformationAvailable(type)) return false;

	const AirportSpec *as = ::AirportSpec::Get(type);
	if (!as->IsWithinMapBounds(0, tile)) return false;

	AirportTileTableIterator it(as->table[0], tile);
	uint dist;
	Town *t = AirportGetNearestTown(as, it, dist);
	if (!::Town::IsValidID(t->index)) return false;

	if (_settings_game.economy.station_noise_level) {
		return GetAirportNoiseLevelForDistance(as, dist) <= t->MaxTownNoise() - t->noise_reached;
	}

	int num = 0;
	const Station *st;
	FOR_ALL_STATIONS(st) {
		if (st->town == t && (st->facilities & FACIL_AIRPORT) && st->airport.type != AT_OILRIG) num++;
	}
	return 1 <= max(0, 2 - num);
}