I am sorry. I am wrong in my calculations. At 150 meters = 492' the max altitude is 852'. At 175 meters = 574' the maximum altitude is 994'. Way over the 400'. I used sin60 and should be tan60 = 1.73. The altitude is 1.73 x distance from the pilot to the fly line assuming that you neglect how tall is the pilot. If we want to be precise we should add the pilot height.

Looks like it is going to be almost impossible to keep the plane below 400'.

Vicente Bortone