Commercial Fixed Wing
Situational Awareness
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural MEL / CDL
General None Reported / Taken
Human Factors; Procedure
[The flight] was released by [another] shift but I took it over. It had 2 conflicting placards that were missed by Maintenance; Dispatch; and the flight crew. The aircraft was already in the air when I took over the desk. I was not notified of error until [the next day] in an email from the Chief Dispatcher. The Auxiliary Power Unit (APU) and the right engine high pressure shutoff valve were both on the deferred list. Per the APU MEL we cannot have the HPSOV on placard. The APU MEL was already on the release and Maintenance added the HPSOV. There is no verbiage in that MEL that says these two MELs can be dispatched.
A Dispatcher reported that he was notified that he had worked a flight that had conflicting deferred items.