Kathmandu is the international airport in Nepal. Typically, the flights arrive in the early afternoon, you have some time to walk around and enjoy dinner that evening.
The departure tax out of Kathmandu is about $26.
From the U.S., you will most likely fly through Bangkok (Thai Air) or another city in Asia, and you will have to overnight in this city. Because of the dateline and the overnight, it takes 3 days to get to Kathmandu. Bangkok has a new airport as of October 2006. AWR can help book a hotel and transfers in Bangkok for you.
From Europe, flights depart from many major cities. There will be at least one stop en route to Kathmandu, depending on the airlines. It is at least 15 hours of travel time one-way.
AWR can help arrange your local and international flights.
For the Everest treks, you will fly into Lukla. There are 30-40 flights a day, but they only fly in the morning and only if there are no clouds. The price is around $100/person one-way.
If the Lukla flights are cancelled, clients are responsible for extra fees including hotel, meals, and transfers. We highly recommend travel insurance, which will pay for these added expenses.