Although it is possible to take scenic flights over Milford Sounds departing from Queenstown and Te Anau, it is better value to take one of the scenic flights that depart from Milford Sound itself.
Air Milford and Milford Sound Scenic Flights operate fixed-wing aircraft from Milford Sound Airport and Milford Helicopters also have flights departing Milford Sound that feature a landing on the Donne Glacier and give you the option of returning to Te Anau.