Born on 2 November 1920 at Wandre, Liège, he enlisted on August 31, 1939, in the artillery. Posted at the Fortress of Namur he was promoted Sgt and he volunteered for pilot at the Aéronautique. At the outbreak of War, he followed the Flying School who was first transferred in France and then to Morocco. He escaped to the UK were he arrived on 5 August 1940. He enlisted in the RAFVR on 13 August 1940 and was send for training at 13 EFTS (23 December 1940), 5 SFTS (2 April 1941) and terminating his training with 58 OTU where he arrived as P/O on 10 July 1941. He joined the Belgian Flight of 131 Sqn on 25 August 1941 and was transferred to the newly formed 350 (BE) Sqn on 14 November 1941. Promoted to F/O on 6 July 1942, (Acting) F/Lt on 29 December 1942 and takes command of "B" Flight. Hospitalized several times during the period between 7 October 1942 and 22 October 1943. F/Lt (WSR) on 6 July 1943 Posted to HQ , 9 Group (3 January 1944), N°2 Tactical Exercice Unit (5 January 1944), RAF Station Lulsgate Bottom (19 January 1944) returning to 350 Sqn on 26 April 1944. on 10 June 1944, C.O. of "A" Flight. Attached to the USAAF on 13 November 1944 where he flew with 336 Sqn of 4 FG ( P-51D). From 21 December 1944 he instructed at the Belgian Training School, joined the 30 Belgian Leave and Rest Centre (3 February 1945) and the School of Air Support (22 March 1945) when War ended. He joined 17 SFTS in March 1946 and was posted to 525 Sqn in April 1946. When the Belgian Air Force became independent,  Plisnier left service and joined SABENA. 

DFC Citiation of 30 August 1943:

"Has served in a fighter squadron since July 1941, and has commanded a flight in 350 (Belgian) Squadron since December 1942. He has participated in 43 sorties during which he has destroyed at least 3 enemy aircraft and damaged 3 others. Troughout his operational career, Flight Lieutenant  Plisnierhas displayed keenness and and efficiency which have set an excellent example."