It seems air transport is popular.
The report also said -
The arrests marked at least the fifth time authorities have intercepted airborne pot shipments since December. The previous four involved float planes.
On a fourth occasion, tribal police seized a float plane on the Columbia River March 14 after disabling it by hurling rocks at the propeller.
The pilot made it to the other side and eluded sheriff's deputies. A man believed to be the pilot was later spotted and arrested on the Colville reservation.