Narrative:

Loss of stabilizer anti-ice in flight; icing conditions between aircraft position and the planned destination. The filed alternate seemed to be the safest option; so the crew began a diversion to their alternate; informed dispatch of the problem and their current plan; and asked if dispatch had a better suggestion.identification: dispatch saw a notification on wsi fusion that the flight was diverting from ZZZ1 (intended destination) to ZZZ (filed alternate). I was initially confused because the weather conditions at ZZZ1 looked good for landing. Then I received an ACARS (there is a 1-3 minute lag time before the message alert comes through) - 'lost anti ice / divert to ZZZ / can you give us icing report or suggest better option.'cause: in flight; while near/above the destination airport; the aircraft lost stabilizer anti-ice capability. Response: I informed maintenance control; who asked if he lost stab anti-ice - I said I was not sure. I sent an ACARS asking the crew; 'what specifically have you lost?' they said 'stab anti-ice.' ZZZ appeared to be the safest option; although according to aviation weather center's icing forecast page; there seemed to be a noticeable risk of icing at lower altitudes. I asked the dispatch supervisor for guidance and he said because they were at FL180 they should be fine. I was confused by what he meant - I clarified that my concern was descending to land; with moisture in the lower altitudes; near the freezing level. (Metar temp at ZZZ was 2C; so the freezing level would have been very close to the surface.) I called wsi and told them what was going on. (ZZZ2-ZZZ1 lost stabilizer anti-ice; diverting to ZZZ; and currently 40 east of art at FL180.) they said there was a risk of light icing in the descent between 10;000 feet and 2;000 feet everywhere in that area. (Lowest cloud layer on the ZZZ metar was above 3;000 feet and we were optimistic that it would be safe once they got below the clouds.) they did not seem to think ZZZ was a bad idea; given the options. We had some extra fuel on board (and the reserve fuel); but not enough that I would have felt comfortable seeking a significantly farther alternate. I did not know how concerned I should be with this flight descending through 7;000 feet of potential light icing. I was very concerned; but did not know how to provide better service/assistance to the crew. At the same time this was going on; we had a captain upgrade class in the [dispatch]. They had been standing by desks 1 and 2 for a while; and headed over to 3/4/5/6 around the time that this situation began; while I was working desk 6. They stood around me and I said; 'this is not a good time.' I believe the instructor said that they could just watch and stay out of my way. I understand that it is good for them to realize that things aren't always quiet and the dispatch can get hectic. However; when I was trying to get a hold of the dispatch supervisor and had to walk around them; it was frustrating to do so. (And there was additional pressure being watched by visitors while I was concerned for the safety of my flight.) we also had 2 representatives from a maintenance contractor visiting the dispatch at the time. The flight landed ZZZ without incident and when the captain called for maintenance he did not sound shaken at all.suggestions: in the past few weeks; I have overheard/observed other dispatchers' handling of loss of anti-ice in flight and I found their responses to be lacking in knowledge of icing condition hazards. I intended to file [report] on these but was unable to find the time. I expressed my concern to management about the two dispatchers involved and also the lack of knowledge and lack of training I believe most dispatchers here (including myself) have with regard to icing hazards in flight. It is one thing to say; 'just get an icing forecast from wsi if you're not sure' for pre-flight planning with a no-icing MEL; but when we are responsible for flight following and operational control; I think we need more training regarding the safe handling of flights that lose anti-ice capability in flight. With wsi's help; I agreed with the crew that ZZZ was the safest option without dipping into our reserve fuel. What I did not know was whether or not it might be worth using the reserve fuel to find a more distant alternate that we could get to and land without descending through icing conditions; or with less of an icing risk; perhaps through fewer altitudes of potential icing. I have observed other dispatchers misinterpret the freezing level and also misunderstand that cruising at an altitude that does not have a risk of icing does not mean that you won't have to descend through icing in order to land. Particularly in the winter months; when the freezing level is close to the surface; we can't just plan to fly below it in order to avoid icing. My suggestion is better training and/or written guidance for dispatchers on how to detect icing risk and how to handle in-flight loss of anti-ice capability.

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Original NASA ASRS Text

Title: Dispatcher reported providing the suitable weather diversion airport due to aircraft loss of anti-ice in flight while in known icing weather conditions.

Narrative: Loss of stabilizer anti-ice in flight; icing conditions between aircraft position and the planned destination. The filed alternate seemed to be the safest option; so the crew began a diversion to their alternate; informed dispatch of the problem and their current plan; and asked if dispatch had a better suggestion.Identification: Dispatch saw a notification on WSI Fusion that the flight was diverting from ZZZ1 (intended destination) to ZZZ (filed alternate). I was initially confused because the weather conditions at ZZZ1 looked good for landing. Then I received an ACARS (there is a 1-3 minute lag time before the message alert comes through) - 'lost anti ice / divert to ZZZ / can you give us icing report or suggest better option.'Cause: In flight; while near/above the destination airport; the aircraft lost stabilizer anti-ice capability. Response: I informed Maintenance Control; who asked if he lost stab anti-ice - I said I was not sure. I sent an ACARS asking the crew; 'What specifically have you lost?' They said 'stab anti-ice.' ZZZ appeared to be the safest option; although according to Aviation Weather Center's icing forecast page; there seemed to be a noticeable risk of icing at lower altitudes. I asked the Dispatch Supervisor for guidance and he said because they were at FL180 they should be fine. I was confused by what he meant - I clarified that my concern was descending to land; with moisture in the lower altitudes; near the freezing level. (METAR temp at ZZZ was 2C; so the freezing level would have been very close to the surface.) I called WSI and told them what was going on. (ZZZ2-ZZZ1 lost stabilizer anti-ice; diverting to ZZZ; and currently 40 east of ART at FL180.) They said there was a risk of light icing in the descent between 10;000 feet and 2;000 feet everywhere in that area. (Lowest cloud layer on the ZZZ METAR was above 3;000 feet and we were optimistic that it would be safe once they got below the clouds.) They did not seem to think ZZZ was a bad idea; given the options. We had some extra fuel on board (and the reserve fuel); but not enough that I would have felt comfortable seeking a significantly farther alternate. I did not know how concerned I should be with this flight descending through 7;000 feet of potential light icing. I was very concerned; but did not know how to provide better service/assistance to the crew. At the same time this was going on; we had a Captain upgrade class in the [Dispatch]. They had been standing by Desks 1 and 2 for a while; and headed over to 3/4/5/6 around the time that this situation began; while I was working Desk 6. They stood around me and I said; 'This is not a good time.' I believe the instructor said that they could just watch and stay out of my way. I understand that it is good for them to realize that things aren't always quiet and the Dispatch can get hectic. However; when I was trying to get a hold of the Dispatch Supervisor and had to walk around them; it was frustrating to do so. (And there was additional pressure being watched by visitors while I was concerned for the safety of my flight.) We also had 2 representatives from a Maintenance Contractor visiting the Dispatch at the time. The flight landed ZZZ without incident and when the Captain called for Maintenance he did not sound shaken at all.Suggestions: In the past few weeks; I have overheard/observed other dispatchers' handling of loss of anti-ice in flight and I found their responses to be lacking in knowledge of icing condition hazards. I intended to file [Report] on these but was unable to find the time. I expressed my concern to management about the two dispatchers involved and also the lack of knowledge and lack of training I believe most dispatchers here (including myself) have with regard to icing hazards in flight. It is one thing to say; 'Just get an icing forecast from WSI if you're not sure' for pre-flight planning with a no-icing MEL; but when we are responsible for flight following and operational control; I think we need more training regarding the safe handling of flights that lose anti-ice capability in flight. With WSI's help; I agreed with the crew that ZZZ was the safest option without dipping into our reserve fuel. What I did not know was whether or not it might be worth using the reserve fuel to find a more distant alternate that we could get to and land without descending through icing conditions; or with less of an icing risk; perhaps through fewer altitudes of potential icing. I have observed other dispatchers misinterpret the freezing level and also misunderstand that cruising at an altitude that does not have a risk of icing does not mean that you won't have to descend through icing in order to land. Particularly in the winter months; when the freezing level is close to the surface; we can't just plan to fly below it in order to avoid icing. My suggestion is better training and/or written guidance for dispatchers on how to detect icing risk and how to handle in-flight loss of anti-ice capability.

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.