Lockheed EC-121 Constellation (53-0554)

Pima Air & Space Museum, Tucson, AZ, 21 Apr 18. More from their website:

Manufacturer: LOCKHEED
Markings: 79th Airborne Warning and Control Squadron, Homestead AFB, Florida, 1974
Designation: EC-121T
Serial Number: 53-0554

LOCKHEED EC-121T WARNING STAR
The commercial success of the Constellation airliner led Lockheed to develop several larger versions of the aircraft. The most produced of these is the Model 1049 Super Constellation that featured a longer fuselage and more powerful engines. This version also proved to be a successful airliner and was one of the last long-range piston engine airliners to see service. Like its earlier cousins the 1049 attracted the attention of the U.S. military and served as transports and electronic warfare aircraft for both the Navy and Air Force. The RC-121D version was built for the Air Force as an airborne radar aircraft and entered service in 1953. They were upgraded several times and eventually were given the designation EC-121T in the early 1970s. The last of them left Air Force service in the late 1970s. In 1967, an EC-121 crew was responsible for the first successful airborne radar controlled interception of an enemy aircraft when they directed an Air Force fighter to a successful shoot-down of a North Vietnamese MiG-21.