It's ok. But, a = XPLMFindDataRef("sim/flightmodel/position/local_y"); XPLMSetDataf(a, 100.0f);, when I write this code it doesn't stay in the sky, it crashes after a while. It means y set once to 100.0f but it changes. I don't want it to change, I want it to remain as 100.0f.