You don't

You shoot him twice in the back of the head. You don’t feel anything while you are doing it. But at the end of the day, the choice was made, and you continue your way towards the cockpit.

To your surprise, you run into the two crewmembers who had some fun time with you in the morning. And now you see them stop, and reach for their guns. The one on the right is fat. You take him slow. The other guy is fit, albeit a bit short. You take him faster than the other.