United will significantly expand its international service next year. On March 28, the carrier will begin daily nonstop service year-round between Chicago O’Hare International Airport and Zurich Airport, flying Boeing 767-300ER aircraft with 46 Polaris business class seats. The airline will also launch a second daily flight that day from Newark to both Amsterdam and Frankfurt. The Amsterdam route will operate on Boeing 767-300ER planes with 46 Polaris seats while the Frankfurt route will employ the same model with 30 Polaris seats. United will also make its Denver International Airport-to-London Heathrow route year-round, pending government approval. In addition, flights from San Francisco to Indira Gandhi International Airport in New Delhi will be year-round, beginning Dec. 5. That route had been announced as seasonal and is the carrier’s first nonstop service from the West Coast to India. It will use Boeing 787-9 Dreamliner aircraft.