B757-200
Dispatch Dispatcher
Communication Breakdown; Confusion; Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Provided Assistance; Flight Crew Overcame Equipment Problem; Flight Crew Requested ATC Assistance / Clarification; General Maintenance Action
Human Factors; Aircraft; Manuals; Procedure
One of my international long range flights had MEL'd items for HF/SATCOM and Basic ACARS. This should have left the flight with two methods of long range communications. Once the flight was airborne it received a reroute. I was able to contact the flight via SATCOM; however they indicated that the problem with the ACARS was incorrect software and that they could not place a SATCOM call. This left them with only one method of long range communications (single HF). I told them that if they needed to contact Dispatch to have ATC call us and that we would call them back on SATCOM. The cause of the problem was the MEL provided no indication that the exact nature of the ACARS problem also rendered SATCOM unusable to the crew. In the future we need to make sure the MEL and other manuals are clear as to the consequences of placarding a particular system inoperative.
A Dispatcher discovered after the fact that the B757-200; dispatched with ACARS and HF Comm MEL's communications systems in actuality only had a single functioning long range communication system.  ATC was enlisted to provide info/data relays if required.