Negative altitude WP in SITL

Dear all,

I tried to fly my quad to a height of -40m from the takeoff point with Mission Plan.
And it succeeded.
Next, I tried same Mission Plan In SITL, but the quad stopped around -18m.

Is there anything to do to fly at negative altitudes in SITL?

it most likely hit the virtual ground

Hi Michael,

So that’s it.

I wish I could remove that restriction, right?

My Quadcopter took off from the top of dam.