Darrah received his commission through the Aviation Officer Candidate Program and was designated a naval flight officer in October 1983.
His operational fleet tours were with Electronic Attack Squadrons (VAQ) 137, 140, 136, Carrier Air Wing Five Strike Operations, and as the commanding officer of VAQ-142. Under his leadership, VAQ-142 completed successful combat deployments to Southwest Asia supporting Operations Northern and Southern Watch and were awarded the Chief of Naval Operations Annual Safety "S" for 2001. During these tours he accumulated more than 3,200 flight hours and 603 carrier landings.
Ashore, he was assigned to VAQ-129 as an instructor; aide to the commander, Space and Naval Warfare Systems Command; Advanced Education Program at George Mason University; information operations planning officer/liaison to Joint Special Operations Command; Airborne Electronic Attack Systems and EA-6B Program Office (PMA-234) advanced systems integrated product team lead. After being designated as a member of the acquisition corps, he served as the first EA-18G deputy program manager when the office was established in January 2003.
During his tenure, the EA-18G program received the 2004 Association of Old Crow’s Integrated Product Team Award and 2004 OSD(AT&L) Packard Award Certificate of Achievement. He was also recognized with the 2004 Admiral Perry Award and 2004 Association of Old Crow’s Metropolitan Chapter Lifetime Achievement Award.
He subsequently served as commanding officer, Pacific Missile Range Facility, Barking Sands, Kauai, Hawaii; and as the F/A-18 and EA-18G program manager from July 2007 to July 2011. After selection to flag, he served as the F-35 Joint Strike Fighter weapon systems program manager from July 2011 to October 2012.
In November 2012, he assumed the position as commander, Naval Air Warfare Center Aircraft Division and the assistant commander for Research and Engineering, NAVAIR. Darrah has been awarded the Legion of Merit (three), Defense Meritorious Service Medal, Meritorious Service Medal, Air Medal (four), Navy and Marine Corps Commendation Medal (four), Navy and Marine Corps Achievement Medal (three) and various other unit awards.