When a packet capture is done on the AirCheck test unit, the timestamp on the packet is taken from the time setting on the AirCheck unit.  This timestamp in the packet capture is assumed to be UTC or GMT time by WireShark.  When WireShark presents the packets, it converts the timestamp in the packet capture (UTC/GMT time) to the local computer time zone.  If you would like to see the same timestamp that is displayed on the AirCheck unit, you can change the View-> Time Display Format on WireShark to "UTC".  The time stamps will now be the same on WireShark as the time on the AirCheck tester.