To overcome this difficulty, a slot is made on the top of the septum for a few millimeter deep with a surgical fissure bur (Fig.4 blue dashed line).  With this flat plane, the pilot drill will make a stable entrance into the septum (Fig.5).

Septum Slot

Xin Wei, DDS, PhD, MS 1st edition 01/02/2015, last revision 01/02/2015