By Air: The Royal Nepal Airline is the national flag carrier of Nepal with flights To/From Delhi, Hong Kong, Mumbai, Osaka, Shanghai and Singapore. Other international Airlines operating From/To Katmandu are Biman Bangladesh Airlines (Dacca), China South-west Airline (Lhasa), Gulf Air (Abu Dhabi), Indian airlines Delhi, Calcutta, Thai Airline (Bangkok) Transavia (Amsterdam via Sharjah) well now have many flights connection from around the world More Flights Schedule
By Land: Some of visitors entering Nepal by land Must use no other entry points other than Kakarbhita, Birgunj, Bhairahawa, Nepalgunj, Dhangadi, Mahendra Nagar and Kodari (China Border)
You could travel to Kathmandu via Bangkok, Hong Kong and Singapore. There are daily flights to Kaathmandu from bankgkok.
If in India, you can fly to Nepal from Delhi, Mumbai, Calcutta, Banglore and Varanasi. There is the spectacular flight from Lhasa to Kathmandu on Saturdays, Tuesdays and Thrusdays operated by China Southwest Airlines. You can also fly Druk Air from Paro in Bhutan, or take a flight from Dhaka, Bangladesh.
From Europe and Middle East
RNAC operates flights into and out of London and Paris via Dubai and Frankfurt.
Pakistan International, Bangladesh Biman and Aeroflot have one-airline service from Europe to Kathmandu.The other option are the charter companies - LTU operates a weekly flight from Germany to Kathmandu during winters.
From North America
You could fly to Nepal via India or alternatively via Bangkok or Hong Kong. RNAC’s Osaka flight makes good connections with North American flights.