if you tell them in time you can go to any destination in the vn network, using an id90 ticket you must be careful as you are always on a sby base, the pricing is ridiculous as you also have to pay the tax for the ticket, so if you go to moscow or australia you would pay usd 650 for a id 90, whilst you could buy a full fare on offer for 850 and be sure to be on the flight!