[1][4] The TA-4S trainers were not the standard TA-4 with a common cockpit for the student and instructor pilot, but were instead rebuilt by Lockheed with a 28-inch (710 mm) fuselage plug inserted into the front fuselage and a separate bulged cockpit (giving better all round visibility) for the instructor seated behind the student pilot.

As such converted/rebuilt airframes, these TA-4S trainers were powered by the original Wright J65 turbojet engines as used in the B/C models instead of the Pratt & Whitney J52 used by the purpose-built TA-4E/Fs tandem-seaters from Douglas assembly line; this was the main reason why the RSAF decided to not procure the TA-4E/Fs (if indeed an order was placed) and then having to maintain two different engines to power essentially the same aircraft type (a scenario not unlike having a fleet within a fleet).

[4] In 1983, a third order of 8 TA-4S saw 16 stored A-4Bs from the Aerospace Maintenance and Regeneration Center being converted and rebuilt as the TA-4S-1 trainers (eight airframes).

[4] With SAI contracted as the main contractor for the upgrading project and a non-afterburning General Electric F404-GE-100D turbofan engine selected as the new engine, the upgrading project would later be extended to cover the entire fleet of newer A-4S-1s as well as taking the opportunity to completely modernize the avionics package (newly installed equipment now included a Pave Penny laser seeker mounted in the nose, an Inertial navigation system (INS), a Tactical air navigation system (TACAN), fore & aft Radar warning receivers (RWR) and chaff/flare countermeasures) of the aircraft.

The type was also operated by the RSAF Black Knights aerobatic display team for precision aerial manoeuvers from 1990 to 2000.

The A-4SU's achievements included flying directly from Singapore to the Philippines, incorporating the RSAF's first air-to-air refuelling mission in 1986,[10] as well as the aerobatic display of the 'red and white' Super Skyhawks flown by the RSAF Black Knights during Asian Aerospace 1990, 1994 and 2000, it was last used by the Black Knights during Singapore's National Day Parade held on 9 August 2000.

[13] Two of the retired A-4SU Super Skyhawks were also donated to the French Air and Space Museum (Musée de l'Air) for static display.

On 12 January 2006, a Certificate of Transfer and Acceptance signing ceremony took place between representatives of the RSAF and the French Aeronautics Museum at Cazaux Air Base in France.

[3] The new squadron then took up the role of advanced jet training, using its aircraft as a lead-in fighter trainer for RSAF pilots.