This is a ps2, you can also obtain a helicopter in "Calm Before The Storm" mission with JD.Ok,First go to the church,When you start "False Idols" get a car near the church,Take a left, and then another left,and then a right, if you can see the bridge, you got it right, go up the bridge and then jump with the car, and while you jump press triangle. and then you jump down to the building of the left of the bridge.And wait until the helicopter reaches your point,when it's close to you, press triangle to hijack the helicopter,and then just go fly with it.