The navigation season for transit passages on NSR starts approximately at the beginning of July and lasts through to the second half of November. There are no specific dates for commencement and completion of navigation; it all depends on particular ice conditions. In 2011 the navigation season on the NSR seaways for large vessels constituted 141 days in total, i.e. more than 4.5 months. In recent years quite easy ice conditions have been observed and that offers more considerable opportunities for operation at the NSR seaways. All NSR seaways are currently located in the area of one-year ice. In the arctic conditions one-year ice grows approximately up to 1.6 metres. Arktika-type icebreaker can open passages through up to 2.3m thick ice. In early July, at the beginning of navigation ice is not pressurized. The ice is broken and easily moved through. In September and October the NSR seaways can be completely free of ice. The vessel may have the same speed as in the open waters. A voyage from Cape Zhelaniya in Novaya Zemlya to the Bering Strait can be travelled at the speed of 14 knots within 8 days. In November the Laptev Sea and the East Siberian Sea are covered with new ice up to 30sm that allows for safe pilotage of a vessel supported by an icebreaker. Therefore, in the current ice conditions vessels can navigate from July until December.