11 November 1940
The Hawker Hardy K4316 (Flight Lieutenant Neville S.F. Tyas, Sergeant H.L. Maltas) of No.237 (Rhodesia) Squadron is sent to bomb vehicles on the Metemma – Gondar road between 10h30 and 12h40. At around 12h30, several Fiat CR.42s of 412a Squadriglia CT took off to intercept the intruder. At the same time, three Gloster Gladiators (Lieutenant Andrew Duncan, Johan J. Coetzer and Servaas de Kock Viljoen) of No.1 (SAAF) Squadron are also on patrol. Both formations meet above Gallabat. In the ensuing fight, a Gladiator Gladiator is slightly damaged, while a victory is claimed by the Italians (Tenente Mario Visintini), as well as two probable (Sottotenente Giovanni Levi and Sergente Maggiore Luigi Baron).
At the same time as four Gloster Gladiators are sent to Sudan, No.2 (SAAF) Squadron received the reinforcement of five pilots, namely Lieutenant Thomas Condon, Edwin A. Jarvis, P.H. Smith, Rolfe A. Gerneke  and John, R.R. Wells.
 No.237 (Rodesia) Squadron : Operations Record Book (Form 540 and Form 541). Kiew : TNA, AIR 27 / 1450.
 EUSEBI E., LAZZARO S., SLONGO L. Le vittorie aeree di Mario Visintini in Africa Orientale, in Storia Militare, n°246, 2014, p. 62 ; SCHOEMAN, Michael. Springbok Fighter Victory : East Africa (1940 – 1941). Nelspruit : Freeworld. p.47 et 137 ; SHORES, Christopher ; RICCI, Corrado. Dust Clouds in the Middle East – The Air War for East Africa, Iraq, Syria, Iran and Madagascar, 1940 – 1942. London : Grub Street, 2010 (Reprinted). p.77 ; GUSTAVSSON, Håkan. Captain Servaas de Kock Viljoen. Biplane Fighter Aces from the Second World War : http://surfcity.kund.dalnet.se/commonwealth_viljoen.htm
 On 30 January 1953, he had the privilege of making the first flight of a South African pilot on a jet (Sabre) aircraft during the No.2 (SAAF) Squadron’s participation in Korea War, with Major John S.R. Wells, also a former member of the Squadron in East Africa.