The city has a domestic airport called Yongphulla Airport where most of the flights are dismissed. You can land at Paro International Airport, from where it's around sixteen-hours long journey to Trashigang.
From Paro, drivers can take Bumthang - Ura Hwy to reach Trashigang in about 17 hours. There are plenty of cabs available which can be hired to reach Trashigang from Paro.
Direct buses are available from Samdrup Jongkhar, Thimphu, Trashiyangtse and Mongar, which take around a day to reach Trashigang.