Narrative:

During cruise flight; we were forced to climb and descend multiple times to avoid potential icing conditions. MEL for left wing anti-ice prohibited operations in known or potential icing conditions. Also; looking ahead the weather was not trending as forecast and potential icing conditions were present there. We sought out an alternate that would allow for clear skies cruise level to surface to avoid icing. [An alternate] was chosen and we made the decision to divert. Direct [to the alternate] was best course of action at cruise flight. Overflying [our original destination] we were advised by company and ATC that we could proceed to original destination without potential icing conditions if we approached [our original destination] from the east and descended safely to an altitude below the cloud deck. We changed destination back to [our original destination] and safely landed as originally planned. The MEL was the cause for concern. Otherwise the diversion was safest course of action until it became visible apparent that we could safely proceed to [our original destination] in VMC conditions.based on the weather info we had prior to departure there as no indication that the flight could not safely proceed to [our original destination] and remain out of icing conditions. However; maybe in the future dispatch could look at icing forecast models and determine that the aircraft should not proceed as planned. The crew would not have this info unless supplied by dispatch.

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Original NASA ASRS Text

Title: The flight crew of a MD11 reported that they departed with an aircraft with an MEL item that prohibited them from entering icing conditions. It turned out; the weather was not as forecast and they had to deviate several times to avoid icing.

Narrative: During cruise flight; we were forced to climb and descend multiple times to avoid potential icing conditions. MEL for left wing anti-ice prohibited operations in known or potential icing conditions. Also; looking ahead the weather was not trending as forecast and potential icing conditions were present there. We sought out an alternate that would allow for clear skies cruise level to surface to avoid icing. [An alternate] was chosen and we made the decision to divert. Direct [to the alternate] was best course of action at cruise flight. Overflying [our original destination] we were advised by company and ATC that we could proceed to original destination without potential icing conditions if we approached [our original destination] from the East and descended safely to an altitude below the cloud deck. We changed destination back to [our original destination] and safely landed as originally planned. The MEL was the cause for concern. Otherwise the diversion was safest course of action until it became visible apparent that we could safely proceed to [our original destination] in VMC conditions.Based on the weather info we had prior to departure there as no indication that the flight could not safely proceed to [our original destination] and remain out of icing conditions. However; maybe in the future dispatch could look at icing forecast models and determine that the aircraft should not proceed as planned. The crew would not have this info unless supplied by dispatch.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.