Narrative:

During climb around fl 290 the captains mcdu froze up. Only the circuit breaker and menu keys worked. I contacted mx to see if they had an airborne fix. The only fix involved pulling a circuit breaker and we determined it was best to wait till we got on the ground. On the arrival to ZZZ; with the autopilot engaged and the first officer as the PF; we were in the process of changing PF/pm duties due to the approach being changed to the runway xxr prm and the requirement that prms be flown by the captain. Both navigation displays lost navigation data. (The magenta line disappeared but vors remained visible) the aircraft remained in LNAV and seemed to stay on course; and the FMS continued to auto sequence to the next fix. I notified approach control of the loss of nav data and asked for a heading and that we would still be able to do the prm. We received a 90 degree heading finished the prm brief and got a turn to base and a lower altitude. During the radio exchange the controller and I stepped on each others calls. I clarified the instructions and my first officer and I proceeded to swapped pm/PF duties. We then got a turn to intercept and the controller asked our speed. My first officer replied 250K was last assigned. The controller in a little of a huff replied slow to 180K as assigned with the last turn. We complied and called airport in sight. We were cleared for the visual runway xxr and landed with no other complications. I feel during the radio exchange earlier I had clarified all the instructions we received and read them back. The controller did not correct my read back and add a new assigned speed. I will admit with all the complications of our nav failure and the previous failure limiting us the use of one mcdu might have distracted us and caused us to miss an instruction from the controller. We did make a read back of the instruction to clarify; with no correction from ATC.

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Original NASA ASRS Text

Title: Loss of both moving map displays distracted the Flight Crew of an ERJ-170 on arrival. A speed deviation and the need for vectors to the ILS result.

Narrative: During climb around FL 290 the Captains MCDU froze up. Only the CB and Menu Keys worked. I contacted MX to see if they had an airborne fix. The only fix involved pulling a CB and we determined it was best to wait till we got on the ground. On the Arrival to ZZZ; with the autopilot engaged and the First Officer as the PF; we were in the process of changing PF/PM duties due to the approach being changed to the RWY XXR PRM and the requirement that PRMs be flown by the Captain. Both NAV displays lost NAV Data. (the magenta line disappeared but VORs remained visible) the aircraft remained in LNAV and seemed to stay on course; and the FMS continued to auto sequence to the next fix. I notified Approach control of the loss of Nav Data and asked for a heading and that we would still be able to do the PRM. We received a 90 degree heading finished the PRM brief and got a turn to base and a lower altitude. During the radio exchange the controller and I stepped on each others calls. I clarified the instructions and my First Officer and I proceeded to swapped PM/PF duties. We then got a turn to intercept and the controller asked our speed. My First Officer replied 250K was last assigned. The controller in a little of a huff replied slow to 180K as assigned with the last turn. We complied and called airport in sight. We were cleared for the visual RWY XXR and landed with no other complications. I feel during the radio exchange earlier I had clarified all the instructions we received and read them back. The controller did not correct my read back and add a new assigned speed. I will admit with all the complications of our nav failure and the previous failure limiting us the use of one MCDU might have distracted us and caused us to miss an instruction from the controller. We did make a read back of the instruction to clarify; with no correction from ATC.

Data retrieved from NASA's ASRS site as of April 2012 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.