Question: Who operates the testing facility at Arnold Air Force Base in Tennessee?

Context paragraphs:
Propulsion Wind Tunnel Facility: The Propulsion Wind Tunnel Facility, located at Arnold Engineering Development Complex, Arnold Air Force Base, Tennessee, holds three wind tunnels: the 16-foot transonic (16T), 16-foot supersonic (16S), and the aerodynamic 4-foot transonic (4T) tunnels.  The facility is devoted to aerodynamic and propulsion integration testing of large-scale aircraft models.  The tunnels are powered by a large compressor plant which allows the wind tunnels to run for extended periods of time.  The test unit is owned by the United States Air Force and operated by Aerospace Testing Alliance.

Aero-propulsion Systems Test Facility: The Aero-propulsion Systems Test Facility, located at Arnold Engineering Development Complex is a unique national facility designed to test aircraft propulsion systems in true mission environments without leaving the ground.  The test unit is owned by the United States Air Force and operated by Aerospace Testing Alliance.

Peterson Air Force Base: Peterson Air Force Base is a U.S. Air Force Base that shares an airfield with the adjacent Colorado Springs Municipal Airport, also having the North American Aerospace Defense Command (NORAD) and United States Northern Command (USNORTHCOM) headquarters.  Developed as a World War II air support base for Camp Carson, the facility conducted Army Air Forces training and supported Cold War air defense centers at the nearby Ent Air Force Base, Chidlaw Building, and Cheyenne Mountain Complex.  The base has been the location of the Air Force Space Command headquarters since 1987 and has had NORAD/NORTHCOM command center operations since the 2006 Cheyenne Mountain Realignment placed the nearby Cheyenne Mountain Complex centers on standby.

Ent Air Force Base: The Ent Air Force Base was an Air Force base located in the Knob Hill neighborhood of Colorado Springs, Colorado.  A tent city, established in 1943 to build the base, was initially commanded by Major General Uzal Girard Ent (1900-1948) for whom the base is named.  The base was opened in 1951.  From 1957 to 1963, the base was the site of North American Aerospace Defense Command (NORAD), which moved to the Cheyenne Mountain Air Force Station.  The base became the Ent Annex to the Cheyenne Mountain facility in 1975.  The facility was closed in 1976 (becoming a Formerly Used Defense Sites).  The Ent Air Force Base site later became the location of the United States Olympic Training Center, which was completed July 1978.

Double cantilever hangar: A Double cantilever hangar is a type of hangar that was constructed by the United States Air Force during the Cold War.  Large hangers were constructed at Castle Air Force Base, Loring Air Force Base, Carswell Air Force Base, and Travis Air Force Base, while smaller hangars were constructed at March Air Force Base, Edwards Air Force Base, Hanscom Air Force Base, and Homestead Air Force Base.

Arnold Air Force Base: Arnold Air Force Base (ICAO: KAYX, FAA LID: AYX) is a United States Air Force base located in Coffee and Franklin counties, Tennessee, adjacent to the city of Tullahoma.  It is named for General Henry "Hap" Arnold, the father of the U.S. Air Force.

Von Karman Gas Dynamics Facility: The von Karman Gas Dynamics Facility at Arnold Engineering Development Complex, Arnold Air Force Base, Tennessee, provide aerothermal ground test simulations of hypersonic flight over a wide range of velocities and pressure altitudes.  The facility consists of three Hypersonic wind tunnels: Tunnel A, B, and C.  The wind tunnels can be run for several hours at a time thanks to a 92,500 horsepower air compressor plant system.  The test unit is owned by the United States Air Force and operated by Aerospace Testing Alliance.

Arnold Engineering Development Complex: Arnold Engineering Development Complex (AEDC), Arnold Engineering Development Center before July 2012, located at Arnold Air Force Base, Tennessee is a ground-based flight test facility operated by the Air Force Test Center.

Mira Loma Air Force Station: Mira Loma Air Force Station is a closed facility of the United States Air Force.  It served as a depot for ICBM missile programs operated at Norton Air Force Base and Vandenberg Air Force Base, California.  It also supported civil defense radiological equipment testing and maintenance.

Bakalar Air Force Base: Bakalar Air Force Base is a former U.S. Air Force base located 4.4 mi northeast of Columbus, Indiana.  During World War II, the base was known as Atterbury Air Field and Atterbury Army Air Base (named in memory of Brigadier General William Wallace Atterbury), but it was renamed Bakalar Air Force Base in 1954 in honor of First Lieutenant John Edmond Bakalar, USAAF.  Established in 1942, the airfield served as a training base for medium-range C-46 Commando and C-47 Skytrain troop carrier planes and glider pilots.  It also was used for training B-25 Mitchell and B-26 Marauder bomber crews.  Reactivated during the Cold War, it was used as an Air Force Reserve training base for troop carrier, tactical airlift, and special operations flying units.  The military base was closed in 1970.  The present-day facility operates as the Columbus, Indiana, municipal airport.

Supporting paragraphs: Aero-propulsion Systems Test Facility Arnold Engineering Development Complex
Answer: Aerospace Testing Alliance