Bluesky Aircraft Create on Ground Keep Moving At Some Airport

[nmfarras]

Hello, I still new in Bluesky. Currently I am trying to try emulating aircraft ground movement. I notice that some airport has more or less accurate altitude position with 1 or 2 feet different so when I create the aircraft at the altitude, the aircraft stop if i set initial speed 0.

On the other hand, some airport can have around 10 ft error. I got this when I try to spawn the aircraft at WIHH which has 84 ft altitude. The aircraft stop when i create it at 75 ft altitude. Just in case, i also try other airport with altitude near it like EHEH, which has 75 ft altitude. I create aircraft at the altitude and 0 speed, and it stop.

I want to know how Bluesky decide if the altitude of the aircraft spawn is on the ground. If my case happen cause the data used as reference is inaccurate, I can try to fix it. Currently the performance model I used is OpenAP.