Harlingen, as an Undergraduate Navigator Training Wing, had as the  primary mission basic observer training. There were two phases: Phase I for Aviation Cadets, and Phase II for Student Officers. The major unit on the base was the 3610th Observer Wing, commanded by Colonel James F. Olive Jr.

The first entrants, the 48 Aviation Cadets of Class 53-01C, began training on June 27, 1952. Early classes were hampered by initial shortages of equipment, experienced instructors, and support facilities. Heroic efforts by all concerned overcame these difficulties in a relatively short time, and great improvements in training and in student moral were soon noticeable.
During 1952, student loads increased from 144 on July 1, to 747 on December 30. On January 22, 1953, the 35 persevering members of Class 53-01C became Harlingen’s first basic observer graduates.
The student load continued to increase, reaching 1314 by June 30, 1953. This expansion would have been even faster except for such limiting factors as a lack of suitable housing, training aircraft, and radar equipment. As new barracks were built and equipment was received, the number of students in training climbed to 1585 on March 31, 1954. The growth continued throughout 1954.

During 1955 and 1956, there were some reductions in the programmed number of graduates. The course was lengthened, four flight missions were added, and the first extended over water navigational training flights went to Ramey AFB, Puerto Rico. A change in student mix occurred, with more AFROTC graduates and fewer Aviation Cadets. The first foreign students (from Ecuador) were entered in the spring of 1956.
Unhappily, the first fatal aircraft accident since reactivating occurred on March 20, 1956. Captain C.J. Bryant and 1/Lt. D.S. Carillo, the only occupants of a Harlingen T-29B which was destroyed near Dobbins AFB, Georgia, died in the crash.

On September 15, 1956, the title of the major course was changed to Primary Basic Navigator (PBN) and the wing redesignated 3610th Navigator Training Wing. Five days later, Class 56-13C became the first to graduate as navigators rather than as aircraft observers.
There were many changes in 1957 and 1958. The programmed student load increased very rapidly; Harlingen assumed a greater share of navigator training as Ellington AFB was closed; electronics training was shifted to the advanced courses at Mather, James Connally, and Keesler Air Force Bases. And Colonel N. L. Calish replaced Colonel Olive as Wing Commander.
In late October and early November, the base broke routine to lend a hand during a civil emergency. Flood relief assistance, in the form of drivers, vehicles, personnel, and supplies, was provided along the lower Rio Grande Valley.
Colonel Callish was promoted to Brigadier General in June 1959, and moved to Mather AFB. Colonel James W. Newsome took command of the 3610th Navigator Training Wing on July 15, 1959. Meantime, training continued to be improved and standardized, and the number of students continued to increase until the peak was reached in the summer of 1960.

Special ceremonies and an Open House was held on March 19, 1960 to mark the graduation of Harlingen’s ten thousandth navigator. Lt. General James E. Briggs, Commander ATC, was guest speaker, and over 25,000 people visited the base on this one day. Also in 1960, Harlingen began pre-flight training for all Cadet Navigators when Lackland AFB phased out of the pre-flight training. And late in the year, PBN was replaced by UNT (Undergraduate Navigator Training).

On March 30, 1961, the Department of Defense would consolidate at James Connally AFB. Harlingen was scheduled to close at the end of the fiscal year, 1962.
When A3C Harold E. Williams signed in on February 7, 1962, he became the last member of all Aviation Cadet Class to enter UNT at Harlingen. Until graduation on June 21, Cadet Williams and his 33 classmates have but one goal in sight, their navigator wings.

The last class of Aviation Cadets to experience Undergraduate Navigator Training at Harlingen departed June 21, 1962.
Neither the oldest nor the largest navigator training base, Harlingen nonetheless has awarded more than 13,000 gleaming, hard earned navigator wings during the last ten years. In the summer of 1960, at the peak of its training load, the base provided daily instruction to 1800 Aviation Cadets and 300 Student Officers.

Thanks to Bill Day (Harlingen 61-09) for writing the above history of Harlingen.

NAVIGATOR HISTORY–

AIRCRAFT: Navigator training of the period commenced in the TC-45 Expeditor or TB-25 Mitchell, followed by transition to the T-29 Flying Classroom, although by the late 1950s, all aircrew training had been consolidated in the T-29. Navigator training for Aviation Cadets was merged with that for commissioned officers and conducted at James Connally AFB, Texas; Harlingen AFB, Texas; Ellington AFB, Texas and Mather AFB, California. Follow-on training qualified some of these navigators in additional fields, such as radar navigator/bombardier,
electronic warfare officer or radar intercept officer.

END OF CADET PROGRAM: The USAF Aviation Cadet program ended for pilots in 1961 and navigators in 1965. In 1960, the Air Force implemented the Undergraduate Pilot Training (UPT) concept. From now on the United States Air Force Academy (started in the fall semester of 1959), The Air Force Reserve Officer Training Corps, and the Air Force Officer Training School were to provide all of its pilots and navigators.

LAST AVIATION CADET CLASS-JAMES CONNALY
The last Aviation Cadet navigator class was 65–15 at James Connally AFB.[12]:73–74 It was made up of Eulalio Arzaga, Jr., James J. Crowling, Jr., Ronald M. Durgee, Harry W. Elliott, Timothy J. Geary, Robert E. Girvan, Glen D. Green, Paul J. Gringot, Jr., William P. Hagopian, Steven V. Harper, Robert D. Humphrey, Hollis D. Jones, Evert F. Larson, Gerald J. Lawrence, Thomas J. Mitchell, Ronald W. Oberender, Raymond E. Powell, Victor B. Putz, Milton Spivack, Donald E. Templeman, and Herbert F. Turney. These aviation cadets became USAF 2nd lieutenants. and were awarded their navigator wings on 3 March 1965. Class 65-15 chose classmate Cadet Steven V. Harper of Miami, Florida, for the honor of “Last Aviation Cadet” based on his high academic, military, and flying grades.