McNab is a Doctor in Oceanographic studies at Stargate Command and at the Atlantis expedition. This person, together with Dr. Moore, studied the oceans of planet M8R-169 in December 2005. With help from their equipment, Lt. Colonel John Sheppard and Dr. Radek Zelenka where able to start up a rescue mission to save Dr. Rodney McKay and Captain Hugh Griffin outside the city of Atlantis. (ATL: "Grace Under Pressure")