Please be aware that some nationals are required to be in possession of an airport transit visa when passing through the international transit area of Oslo airport. Starting from 24th of August 2018, Turkish nationals will be required to obtain a transit visa when transiting at Oslo airport (Gardermoen).
If you are arriving at Oslo airport from a non-Schengen country and departing to a non-Schengen country, you may stay within the premises of the transit area at the airport. Most travelers will in this case not need a visa, as they will not cross the external Schengen border. However, some nationals are required to be in possession of an airport transit visa. This applies to nationals from: Afghanistan, Bangladesh, Democratic Republic of the Congo, Eritrea, Ethiopia, Ghana, Iran, Iraq, Nigeria, Pakistan, Somalia, Sri Lanka, and from 24thAugust 2018 also nationals from Turkey.
Travelers who arrive at Oslo airport for transit only, have to be aware that the transit area at the airport is closed between 11 p.m. and 6 a.m. every day. If your arrival and the time of departure of your connecting flight makes it necessary to stay at the airport between 11 p.m. and 6 a.m., you cannot use the transit area as it is closed during this time. All travelers will then have to pass the border control in order to stay at the airport’s non-transit area or a nearby hotel. This means that those nationals, who must be in possession of a visa when crossing the external Schengen border according to Annex 1 of the Visa Handbook, may need a Schengen visa even if they are only transiting Schengen in Norway. In addition, persons who need to check out and check in their luggage at the airport (normally when using different airlines) also have to go through the border control, even if they are only transiting. Check your luggage tag to see if this applies to you.
Requirements for a Schengen visa for the purpose of transit may be a document explaining why the applicant needs to exit the transit area of the airport, the flight ticket to the final destination and, if required, the visa to the final destination. If the applicant needs a stay over in Norway in order to await the connecting flight, documentation on hotel reservation and funds to cover the stay in Norway should also be provided.
(Royal Norwegian Embassy in London)