Swiss International Air Lines will change the frequency of services from Zurich, Geneva and Basel and increase flight numbers to Beijing, Chicago and Newark.
From Zurich, the carrier will raise the frequency to Prague from three to four times daily and add a second daily flight to Bucharest.
The airline will increase the frequency of Zurich-Chicago flights from once per day to eleven times per week and increase Zurich-Newark flights to once daily. The carrier will deploy Airbus A340s on the routes.
Swiss will raise the frequency on the Zurich-Beijing route from five times weekly to once daily flights, starting at the end of May. Services from Zurich to Cairo will be reduced to four times weekly while those to Cameroon will be withdrawn "for economic reasons", said the airline.
From Geneva, the carrier will add a third daily flight to Nice.
Under a codeshare deal with Darwin Airline, the carrier now offers flights to Luxembourg, Genoa and Lugano from Geneva, effective 8 March. Additionally, the codeshare deal will expand to include Florence and Venice with the start of the summer schedules.
The carrier will reduce its capacity to the UK, Benelux and Germany from Zurich.
Swiss will resume services to London City from Basel Mulhouse Freiburg with twice daily flights, starting 21 May. The airline will withdraw direct flights to Copenhagen, Budapest and Manchester from Basel.
The carrier's service from Basel to Brussels will now be served twice daily by its sister carrier, Brussels Airlines.
In addition, Swiss charter operation Edelweiss Air will fly the twice-weekly Zurich-Tokyo flights for the summer schedule.