This happened during takeoff.
At approximately 75 feet the dual student told the CFI to "take the airplane; we've got to go down now". The CFI replied "ok my airplane". With no runway left to land, the CFI attempted to add full power to conduct a go-around. The dual students hand remained on the throttle, and prevented the CFI from regaining full control of the airplane. The CFI told the dual student that he had to conduct a go-around, but the dual student responded "no we have to get down now". The CFI instructed the dual student to "let go of the throttle; my airplane; we need full power". The CFI attempted to add full power but the dual student continued to pull the power back to idle. The CFI yelled at the dual student "you're going to kill us; let go!" The CFI applied full elevator back pressure and the airplane collided with the airport fence.
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http://www.airsafety.com/reports/ROW041008A.pdf>
