The three ex-PanAm aircraft, all with digital autopilts, and after a period of storage, received modifications for military radios and performed a passenger-only role with underfloor freight as C2/C2A variants.

The remaining six aircraft were flown to and stored at Bruntingthorpe Aerodrome, having been purchased by AGD Systems Corp in anticipation of a later sale.

At the same time, British Airways wished to dispose of its Lockheed L-1011-500 aircraft, and so put in a joint bid with Marshall Aerospace of Cambridge to supply six TriStars.

[2] The RAF's Tristars were subject to progressive updating throughout their operating life; including the fitting of flight deck armour and Directional Infrared Counter Measures to protect against ground fire when flying into Iraq.

During doubts over the FSTA programme, Marshall Aerospace offered to buy and convert some of the large number of surplus commercial TriStars as tankers, but this was rejected.

[7] The initial converted L-1011-500 to be delivered to the Royal Air Force was TriStar KC1 ZD953 (ex- G-BFCF) on 24 March 1986, when it was handed over at Cambridge Airport by Sir Arthur Marshall.

[11] On 6 January 1991, a single TriStar K1 with two crews was deployed to King Khalid International Airport, near Riyadh in Saudi Arabia, its role as a tanker.

[12] After the outbreak of the Bosnian War in April 1992, the United Nations passed Resolution 781 on 9 October, banning military flights over Bosnia and Herzegovina.

[13][16] After the situation escalated in the 1999 Kosovo War, three Tristars were deployed once more to Italy under Operation Engadine in order to support NATO aircraft.

[10] Over the course of Op ENGADINE, five TriStars operated in the theatre delivering 13,500,000 pounds (6,100,000 kilograms) of fuel to 1,580 receiver aircraft across 230 missions.

However, due to the Strategic Defence and Security Review of 2010, these upgrades were halted and ZD949 was left at Cambridge Airport to be used for spare parts.

[18][23][24] In 2017, Tempus Applied Solutions, an aerospace company based in the United States, procured the six remaining ex-RAF Tristars for further use.

The company's intention was to restore three of the AAR tankers to service in that role, providing additional probe and drogue aerial refuelling capacity to the United States Navy and NATO nations that utilise that particular method.