Excuse my ignorance, but where exactly is the gate at which you are told that you don't have enough flying skill to enter? I can't seem to find it despite being around the LS airport about 5 times.
Go to your map-- zoom in on airport-- now look for the big LAX type circular control tower--just north of this there should be a couple of roads that go east-west--on the northern one start heading east (you may have to go east a little befor cutting up to this road as I believe its a highway ramp and is off the ground-- as you get away from the control tower there will be wall on your right (runway area border)-- follow this wall a short distance and there will be a gate on your right--thats it.
in otherwords--on the north side of the eastern end of the airport.
Here is where you go to get into the airport without a license. At the end of the arrow is where you park a car then jump on the car then jump over the fence.
Im using a section of the map that VIPERGTSR01 posted in another thread.