The Aviation Section, Signal Corps, was the aerial warfare service of the United States from 1914 to 1918, and a direct statutory ancestor of the United States Air Force. It absorbed and replaced the Aeronautical Division, Signal Corps, and conducted the activities of Army aviation until its statutory responsibilities were suspended by President Woodrow Wilson in 1918. The Aviation Section organized the first squadrons of the aviation arm and conducted the first military operations by United States aviation on foreign soil.

The Aviation Section, Signal Corps, was created by the 63rd Congress (Public Law 143) on 18 July 1914 after earlier legislation to make the aviation service independent from the Signal Corps died in committee. From July 1914 until May 1918 the aviation section of the Signal Corps was familiarly known by the title of its administrative headquarters component at the time, seen variously as the Aeronautical Division, Air Division, Division of Military Aeronautics, and others. For historic convenience, however, the air arm is most commonly referred to by its official designation, the Aviation Section, Signal Corps (ASSC), and is the designation recognized by the United States Air Force as its predecessor for this period.

The Aviation Section began in turbulence, first as an alternative to making aviation in the Army a corps independent of the Signal Corps, then with friction between its pilots, who were all young and on temporary detail from other branches, and its leadership, who were more established Signal Corps officers and non-pilots. Despite the assignment of Lieutenant Colonel George O. Squier as chief, to bring stability to Army aviation, the Signal Corps found itself wholly inadequate to the task of supporting the Army in combat after the United States entered World War I on 6 April 1917. It attempted to expand and organize a competent arm but its efforts were largely chaotic and in the spring of 1918 aviation was removed, first from the jurisdiction of the Office of the Chief Signal Officer where it had resided since its inception, and then from the Signal Corps altogether. The duties of the section were not resumed following World War I and it was formally disestablished by the creation of the Air Service in 1920.

The Aviation Section, Signal Corps, was created by the Act of 18 July 1914, Chapter 186 (Public Law 143, 63rd Congress), 38 Stat. 514, to supersede the Aeronautical Division, an administrative creation of the Signal Corps within the Office of the Chief Signal Officer (OCSO), as the primary agency for military aviation. Earlier legislation to make the aviation service independent from the Signal Corps died in committee after all officers connected with aviation save one, Captain Paul W. Beck, testified against it. Later provisions of the National Defense Act (39 Stat. 174), 3 June 1916, and the Aviation Act (40 Stat. 243), 24 July 1917, permitted aviation support functions to be gradually transferred from the Aeronautical Division to newly established aviation section organizations. The new law established the purpose and duties of the section, authorized a significant increase in size of U.S. military aviation to 60 officers and 260 enlisted men, increased the size of the Signal Corps by an equal number of personnel to provide them, stipulated that pilots be volunteers from branches of the line of the Army, and detailed them for four years. The Aeronautical Division then became the administrative component of the Aviation Section until its abolition in 1918. The first funding appropriation for the Aviation Section was $250,000 for fiscal year 1915.

The new law also decreed restrictions that only unmarried lieutenants of the line under the age of 30 could be detailed to the section, provisions which encouraged a lack of discipline and professional maturity among the aviators that handicapped the growth of the service, hampered retention of pilots, and prevented flying officers from commanding flying units. Officers on aviation duty who were promoted to permanent captain in their branch arm were automatically returned to the line. Aggravating the situation, the 11 remaining pilots of the 24 previously rated as military aviators all had their ratings automatically reduced to junior military aviator (and therefore incurred a 25% reduction in flight pay) when requirements were changed to include three years experience as a JMA before qualifying for the higher rating. This placed them on the same level as newly graduated pilots, and none of those so reduced regained their ratings before 1917.

At its creation, the Aviation Section had 19 officers and 101 enlisted men. The Aeronautical Division, a quasi-headquarters (Lieutenant Colonel Samuel Reber, Washington, D.C.) with three officers and 11 enlisted men, issued orders in the name of the chief signal officer (CSO). All other personnel of the aviation section were organized on 5 August 1914, by Signal Corps Aviation School General Order No. 10 into the:

totaling 16 officers, 90 enlisted men, seven civilians, and seven aircraft.

Most of the air service had just returned to San Diego from detached service in Texas for the second time in as many years to support Army ground forces in a possible war with Mexico over the Tampico Affair. The impending war was defused by the resignation of Victoriano Huerta on 15 July.