Paro Airport is the only airport in Bhutan while Druk Air is the only airlines of the country. This Royal Bhutan Airlines is the national carrier of the Royal Government of Bhutan and is the only airline allowed to fly into Bhutan. It operates to seven cities in six countries. Travelers do not have much choice of choosing their flights while traveling to Bhutan but Druk Air is a good airline. It has two British Aerospace jets, BAe 146s that are designed and crafted carefully to suit the high altitude landings and takeoffs. The aircrafts are well maintained and pilots are specially trained and have international license for mountain flying. Till date, Druk Air has an immaculate safety record.
Paro International Airport is one of the highest airports in the world and you would prefer window seat while flying to Bhutan because of some of the most fabulous views, you get to see. You can see Himalayas, Mount Everest and Chomolhari from the flight. There are international flights several times a week to and from Bangkok, Kathmandu, Delhi & Calcutta and Dacca. You can check for the schedule at Druk Air official site. It is better to book your seats in advance, especially, for the peak season to avoid the rush. Druk Air only issues the tickets when the Home Ministry of Bhutan approves your visa and the whole procedure can take about a week.
Make sure that your passport details and visa information is exactly the same or you will not be allowed to fly on Druk Air and authorities are very strict about it. If you are combining your visit to Bhutan with visit to India such as to Sikkim and Darjeeling, you may want to enter and depart Bhutan by surface road through the border town of Phuentsoling, which is the only official point of entry into Bhutan. You may also want to fly into Bhutan and exit by road through Phuentsoling or enter Bhutan by road and depart from it through the flight. This is possible but you still need to get your visa approved to get air-tickets.
Druk Air also has domestic and mountain flights packages, designed especially to promote the travel and tourism industry of Bhutan. The Royal Druk Holidays were conceived by the airlines to better utilize its resources and increase distribution points in Bhutan to promote tourism better in the country. They aim to emphasize on the off-season of tourism industry in Bhutan, when less people visit the country. The packages are marketed through interline partners and agencies of Druk Air worldwide. Bhutan Tourism Corporation Ltd is the ground operator for the Royal Druk Air Holidays in the country.