 Qualification as a naval aviator required a demanding 200 hours in the air, so most older officers opted for the less rigorous designation of naval aviation observer, which required only 100 hours in the air.Horne qualified as a naval aviation observer along with most of the other captains in his class, which included future three- and four-star admirals Joseph M. Reeves, Harry E. Yarnell, Alfred Wilkinson Johnson, and Henry V. Butler.After serving as a member of the Naval Examining Board in the Navy Department, Horne temporarily relieved Captain Ernest J.