Image kindly provided by Jan Safarik

During the Hungarian attacks on Slovakia on 23-24 March 1939, the 45th and 49th letka operated from Spišská Nová Ves airfield. These units were equipped with Avia B-534s. The units were severely short on flying personnel due to the departure of personnel of Czech nationality to the Protectorate.
Commander of the 45th letka was J. Svetlik and he had to his disposal six pilots (J. Pálencek, J. Hergott, František Hanovec, Martin Danihel, J. Zachar and Jaloviar).
Commander of the 49th letka was Ján Prhácek and he had to his disposal four pilots (C. Martiš, Š. Devan, Michal Karas and M. Žiaran).

At the time of the invasion of Poland Viliam Jaloviar still served in the 45th Flight, flying Avia-B534s.

During the German invasion of Poland, Slovak fighters clashed with Polish aircraft.
Three B-543s from the 45th letka flown by František Hanovec, M. Žiaran and Jaloviar took off from Naršany on 6 September. At 12:18 (alternatively 08:06), they intercepted a Polish R-XIII near Presov from 56 Squadron, which was on an artillery spotting mission and shot it down. The pilot E. Porada parachuted but was taken POW while the observer M. Piasecki was killed.

Viliam Jaloviar was KIFA on 9 September while performing aerobatics near Presov in B-534 no. 367.

At the time of his death Jaloviar was credited with one shared biplane victory.

Claims:

Kill no.	Date	Time	Number	Type	Result	Plane type	Serial no.	Locality	Unit
	1939
	06/09/39	12:18	1/3	R-XIII (a)	Shared destroyed	Avia B-534		near Presov	45th Flight

Biplane victories: 1 shared destroyed.
TOTAL: 1 shared destroyed.
(a) Polish R-XIII from 56 Squadron shot down. The pilot E. Porada was taken POW while the observer M. Piasecki was killed.

Sources:
Most of this information is prepared by Ondrej Repka with kindly permission of Mr. Stano Bursa.
Air Aces Home Page - Jan Safarik
Avia B-34, B-534 a Bk-534, slovenských pilotov 1939-1944 – Peter Šumichrast and Jozef And’al, 2006 HT model špeciál, ISSN 1335-3667
S.Bursa - personal archive and dates from a prepared book about the 13th fighter flight.
Nieco o clenoch 13.letky (Historie a plastikove moedarstvi) - S.Bursa, 1&2/1997
Slovak Airmen 1939-1945 - J.Rajlich, J.Sehnal, 1991
Slovenske letectvo 1939-1944 - J.Rajninec, 1997
VVS Slovakiib (Aviacia i Vremya 1/99) - V. Kotlobovkiy, 1999 (via Ondrej Repka)