As per the GDS'es no EWR flight on Apr 1:
OS RESPONSE ** DIRECT CONNECT PARTICIPANT **
** AUSTRIAN AIRLINES - AN ** 23 WE 01APR 0000
13OS* 87 J9 C9 D9 Z9 Y9 B9 M9 U9 H9 VIEJFK 1045 1355 772 0
G0 Q2
14OS* 71 J9 C9 D9 Z9 P9 Y9 B9 M9 U9 VIEYYZ 1035 1410 767 0
H9 G0 Q9 V5 W1
15AC 718 J6 C6 D2 Z0 P0 Y9 B9 M9 U9 LGA 1615 1748 E90 0
H9 Q9 V9 W9 G9 S9 T9 L9 A4 K2 R0
16OS* 71 J9 C9 D9 Z9 P9 Y9 B9 M9 U9 VIEYYZ 1035 1410 767 0
H9 G0 Q9 V9 W9 S6 T6 L2
17UA*8232 F4 A4 P0 Y7 B7 M7 U7 H7 Q7 LGA 1615 1748 E90 0
V7 W7 S7 T7 L7 K7
18OS* 71 J9 C9 D9 Z9 P9 Y9 B9 M9 U9 VIEYYZ 1035 1410 767 0
H9 G0 Q9 V9 W9 S6 T6 L2
19UA*8200 F4 A4 P4 Y7 B7 M7 U7 H7 Q7 EWR 1635 1817 E90 0
V7 W7 S0 T0 L0 K0
20OS* 71 J9 C9 D9 Z9 P9 Y9 B9 M9 U9 VIEYYZ 1035 1410 767 0
H9 G0 Q9 V5 W1
21AC 740 J5 C5 D5 Z5 P4 Y9 B9 M9 U9 EWR 1635 1817 E90 0
H9 Q9 V9 W9 G5 S1 R2.