The MFI-17 Mushshak trainer aircraft, crashed near the hills of Ziarat, about 40 kilometres east of provincial capital Quetta.
"Two pilots were wounded in the incident," the army said.
They were later airlifted to a military hospital in Quetta for treatment and were in a stable condition.
The incident is under probe and the cause of the accident is not yet known.
Mushshak aircraft are widely used in Pakistan for training undergraduate student pilots.
The MFI-17 Mushshak is fitted with blind flying instrumentation. It is propelled by a single Textron Lycoming 4-cylinder engine with one twin-blade propeller.