Date: 201403
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: IMC
Weather elements / visibility: Icing
Aircraft: Regional Jet 900 (CRJ900)
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Descent
ATC / advisory: TRACON ZZZ
Aircraft component: Ice/Rain Protection System
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness; Workload; Distraction
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Aircraft Equipment Problem Less Severe
Detector: Person Flight Crew
When detected: In-flight
Result: Aircraft Equipment Problem Dissipated; Flight Crew Executed Go Around / Missed Approach; Flight Crew Overcame Equipment Problem; General Declared Emergency
Contributing factors: Aircraft; Human Factors; Procedure; Weather
Primary problem: Aircraft

Narrative: On the STAR arrival at 280 KTS; the ICE caution displayed in IMC. Since we had previously selected the Cowl Anti-Ice on; I requested and the First Officer; pilot monitoring (PM); selects the Wing Anti-Ice on. Just after passing BLNKR at 8;000 FT and at 210 IAS; the EICAS displayed the ANTI-ICE DUCT warning message. It then disappeared 3-5 seconds later as the ANTI-ICE DUCT caution displayed. I checked the Anti-Ice synoptic page and noted the anti-ice bleeds had closed. The PM immediately started the ANTI-ICE DUCT non-normal checklist. As we had light ice building on the windshield wipers; I requested the PM query the forward flight attendant to look at the wings for signs of ice build-up. She reported 'frost' which I understand to mean light ice; on the forward part of the wings. I did this due to the time constraints of being on downwind for the approach while at the same time descending to below 8;000 FT; and the fact the First Officer was running the non-normal checklist. I felt it would not have been prudent to send the PM back to check the wing for ice. I was using my available resources for information. The non-normal checklist stated to 'Leave Icing Conditions.' If I recall correctly; the ATIS reported 700 broken; 3 SM; and light rain at 1 degree C; I assumed icing conditions would extend all the way to the runway. I also knew the tops were well above our present altitude. I elected to declare an emergency to insure priority handling and land as soon as possible. At the same time; I requested 250 KTS to attempt to disperse any ice that had built up on the aircraft. Since we were given vectors and cleared for a close-in ILS approach for 5L; I was unable to hold the speed for any substantial length of time. However; I had not switched to 'green' needles and the PM had not sequenced the approach. During this time; because of the icing concerns; I was watching the PM perform the non-normal checklist.  I wanted to know where he was in the checklist and if we had to use flaps 20 due to the ice accretion; which I recalled from my study of the non-normal section of the CFM. The non-normal checklist calls for turning the Wing Anti-Ice switch back on; which he did; if ice is not dispersed from the increase in airspeed. Instead of focusing on flying the aircraft; I was trying to figure how to configure for approach. Because I had split my focus and the approach was not sequenced; I flew thru the final approach course 2 times and was re-vectored by ATC. I believe the task saturation on the PM may have caused him to miss that the Wing Anti-Ice was working. At the point in the checklist which verifies if the Wing Anti-Ice is working; I stated we would be landing with flaps 20. The PM meanwhile; per the checklist; selected the flap override in anticipation of landing flaps 20 per my instruction. After receiving the 3rd vector to intercept the localizer; I noticed we were abeam the FAF for ILS 5L; I requested and the PM selected flaps 30 (an error on our part since at that time we were planning a flaps 20 landing but due to my division of attention; my airspeed was slower than desired; but still higher than the flaps 20 maneuvering speed). I also selected a lower altitude in the altitude pre-selector to allow the aircraft to descend lower when the localizer did capture. I started a very shallow descent at this point due the short approach during the emergency. At this point; while flying thru the localizer course the third time and given our position and aircraft state; I decided to go-around. I requested a box vector back around to establish a safer; stabilized approach. ATC assigned a climb to 3;000 FT and vectors back to the ILS 5L. During the go-around; we noticed the Wing Anti-Ice was working without any warning or caution messages. We followed ATC's vectors; shot the approach using normal flaps 45 procedures; landed and taxied in without incident.   To prevent events like this; I recommend taking enough time to perform the non-normal checklists; read the checklists thoroughly; and carefully monitor pre-conceived conceptions of checklists. Also; I should have considered assigning the First Officer the flying duties while I completed the non-normal checklist since I; as PIC; am responsible for the final decisions.


Second narrative: [Report narrative contains no additional information].


Synopsis: CRJ-900 Captain reported Anti-Ice Duct warning message on arrival and declared an emergency to expedite clearing icing conditions. After some confusion and distraction regarding QRH procedures; approach became unstabilized and go-around to a successful landing was accomplished.