Date: 201703
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: IMC
Aircraft: MD-80 Series (DC-9-80) Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Parked
Aircraft component: Window Ice/Rain System
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Dispatcher
Reporter qualification: Dispatch Dispatcher
Human factors: Distraction; Situational Awareness
Second reporter function: Other / Unknown
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Maintenance
When detected: Aircraft In Service At Gate
Result: General Maintenance Action
Contributing factors: Aircraft; Human Factors
Primary problem: Human Factors

Narrative: MD80 tech called 5 min prior to departure to ask if we were able to apply MEL 30 [for] Flight Deck Windshield Anti-Ice System which has a no icing restriction. After reviewing the weather I determined that icing was not a factor. I requested the captain to call me to discuss the weather and MEL. Tech was conferenced in to finalize approval. At the end of the conversation tech requested to add [a different MEL 30]. As I scrolled down the MEL page I saw that there was not a dispatch restriction but missed the fact that the windshield anti-ice system had to be operative in order to apply this second MEL.


Second narrative: The Captain contacted me at departure time with an issue involving the windshield anti-ice; or anti-fog. The Captain was explaining the discrepancy; and stated the windshield anti-ice and anti-fog were both on for some time as they completed their pre-flight. He said an electrical arc emanated from the center of his windshield. While talking with the Captain I was looking to see if there was any history on this aircraft regarding this or similar issue (there was none). In addition to that I also consulted the Aircraft Maintenance Manual to help in identifying or isolating the cause of the arcing. During the course of our conversation; the call was interrupted; the Captain pausing our conversation to talk to other crew members. As the conversation continued I was unable to verify if the arcing was due to windshield anti-ice; or anti-fog.During the time that our conversation was interrupted I quickly referenced the MEL list and noticed that [two] MELs would address both issues. I also had taken note that both discrepancies were flight crew placard-able; and would require Lower Minimums.The Captain and I referenced the MELs and had a discussion about having the systems on during flight and also discussed the circuit breakers as to whether the circuit breakers should be in or out; at which time I quickly looked up the location of the breakers.With [multiple applications] open on my computer I started the required computer entries for the discrepancies and the [approach] downgrade. During the process of entering these items I had 'failed to respond' to one of my entries causing me to have to re-enter the entire MEL item. In fact; I had to close the application on my computer and restart it. I issued both MELs (Anti-Ice and Anti-Fog); and [the] LMP Downgrade. It was at this time I put the Captain on hold and contacted Dispatch for their approval on the MELs [approach] downgrade.There are numerous contributing factors that resulted in this error. This entire event occurred during a time when our phone call volume was very high; forcing me to take call after call without completing the follow-up required for the previous calls.The first issue to arise was interruptions in the communication process; after the Captains interruption the conversation did not pick up right where it left off adding to the difficulty of trying to identify the root cause of the discrepancy. I would also add that the program failure is analogous to a communication failure. The second issue was the distraction for the interrupted call; coupled with trying to reference several technical documents during the same time period.The third issue I was dealing with was fatigue. This call came towards the end of an extremely busy 12 hour shift. Then; adding to the problem; is the number of resources that are required to complete one task. If you couple the above items with the pressure of the aircraft being at departure time; and the stress related to that; your rational approach to problem solving is deteriorated.I am certain; looking back on this incident that the accumulation of these factors coupled together with the fact that there are only 2 Maintenance Controllers on this shift and my relative inexperience with these particular MELs; all contributed to this error.If an MEL is contingent on another system being operative; the contingency should be highlighted in bold text using upper case letters. This text should be highlighted and written below the item identification number and title column; highlighted and written in the Remarks or Exceptions column; and highlighted and written in the procedures section. My first and foremost task will be to 'slow down' mentally during periods of activity like this. I truly believe that self-imposed time pressure was the main factor resulting in my error. I will continue to keep my schedule as consistent as possible to minimize fatigue. If necessary; I will leave calls ringing in the queue so I may fully address the current call.


Synopsis: MD80 Dispatcher and two Maintenance technicians reported an inappropriately applied MEL concerning window heat and anti-fog. The aircraft flew three legs before the error was discovered.