International airport is located in Paro, western Bhutan. Bhutan’s National airline Drukair operates regular flights from New Delhi, Kolkata, Guwahati, Mumbai, Bagdora, Bodgaya (seasonal), Kathmandu, Dhaka, Bangkok and Singapore. Bhutan Airlines operates from Bangkok to Paro via Kolkota and vice versa.
Domestic flights are available for Bumthang(Central), Trashigang(East) and Gelephu(South). They are operated by Drukair and Bhutan Airlines (now not available).
You can enter Bhutan through 3 checkpoints – Phuentsholing and Gelephu in the South and Samdrup Jongkhar in the southeast. Bagdogra airport, in the state of West Bengal (India) is the nearest airport about five hours drive from Phuentsholing. Also Bagdogra (Siliguri) is a convenient point for visiting the West Bengal region of Darjeeling, Kalimpong and the state of Sikkim.