Motion Guide
Open plane.fla
Right click on frame 20 and insert a keyframe.
Next click on the add motion guide icon, this will add a layer above the plane layer.
Select the ppencil tool and on the motion guide layer draw a path for the plane to follow.
Now select the first frame on the plane layer and in the properties panel change the tween options to motion. Then make sure that the snap option is checked as below. You need to make sure the little circle that is in the middle of the plane when you have it selected is attached to the line.
Select frame 20 and add a motion tween and check the snap box, this time ensure that the plane is at the end point of your motion tween.
Control / Test Movie to see the animation. You will notice that the plane follows the line but it is not very realistic.
Excercise
See if you can add additional keyframes to the animation and the free transform tool to make the flight path more realistic.
