static void AddHelicopterToMaps(bool const add, RefuelSite const& r)
{
	GridNo const grid_no = r.grid_no;
	INT16  const ostruct = r.heli_ostruct;

	// are we adding or taking away
	if (add)
	{
		AddHeliPiece(grid_no,       ostruct    );
		AddHeliPiece(grid_no,       ostruct + 1); //here the exception is thrown
		AddHeliPiece(grid_no - 800, ostruct + 2);
		AddHeliPiece(grid_no,       ostruct + 3);
		AddHeliPiece(grid_no,       ostruct + 4);
		AddHeliPiece(grid_no - 800, ostruct + 5);

		// ATE: If any mercs here, bump them off!
		INT16 sCentreGridX;
		INT16 sCentreGridY;
		ConvertGridNoToXY(grid_no, &sCentreGridX, &sCentreGridY);

		for (INT16 y = sCentreGridY - 5; y < sCentreGridY + 5; ++y)
		{
			for (INT16 x = sCentreGridX - 5; x < sCentreGridX + 5; ++x)
			{
				BumpAnyExistingMerc(MAPROWCOLTOPOS(y, x));
			}
		}
	}
	else
	{
		// remove from the world
		RemoveStruct(grid_no,       ostruct    );
		RemoveStruct(grid_no,       ostruct + 1);
		RemoveStruct(grid_no - 800, ostruct + 2);
		RemoveStruct(grid_no,       ostruct + 3);
		RemoveStruct(grid_no,       ostruct + 4);
		RemoveStruct(grid_no - 800, ostruct + 5);
	}

	InvalidateWorldRedundency();
	SetRenderFlags(RENDER_FLAG_FULL);
}