Narrative:

Cruise fight at 35000 feet. Issued instructions by ATC to descend to 34000 feet for crossing traffic. Selected new assigned altitude and initiated descent via flight level change. Within 200 feet of beginning descent a red icon appeared on TCAS indicating an aircraft less than 1;000 feet below at 12 to 1 o'clock climbing toward us. TCAS issued an aural monitor vertical speed and indicated a level off. First officer (pilot monitoring) advised ATC we were responding to a TCAS RA; and a level off was initiated. TCAS indicated conflict aircraft was 400 feet below and climbing toward us. I initiated a climb away from the conflict aircraft. TCAS continued to indicate conflict aircraft was climbing and maintaining a 400 feet separation while we were climbing until passing off our right side. While climbing in response to the RA; ATC issued instructions to climb to 35000 feet. After conflict aircraft passed we leveled off at 35000 feet. As conflict aircraft passed we identified it visually as an EMB175. TCAS conflicting aircraft icon disappeared from TCAS as the aircraft passed us. We resumed cruise flight at 35000 feet. Shortly after the resolution of the event ATC asked if we had received a TCAS RA. Several minutes prior to the event we had been instructed to descend from 37000 feet to 35000 feet. No traffic icons were displayed on the TCAS when issued instructions to descend to 34000 feet. The first indication of any aircraft in our vicinity was the pop up of the red icon. No progression from cyan to amber to red or an aural 'traffic' advisory. After the conflicting aircraft passed; the red icon just disappeared. No transition to amber or cyan. TCAS indicated the conflict aircraft was climbing throughout the event. Controller workload did not sound excessive and the only other aircraft on frequency did not have a similar call sign. We were in cruise flight and both I and the first officer clearly heard the ATC instruction to descend to 34000 feet. The first officer clearly repeated the instructions to ATC. I do not recall any frequency congestion as the instructions were issued and read back.

Related reports:

Google
 

Original NASA ASRS Text

Title: EMB-175 Captain reported responding to a TCAS RA for traffic below while descending from FL350 to FL340.

Narrative: Cruise fight at 35000 feet. Issued instructions by ATC to descend to 34000 feet for crossing traffic. Selected new assigned altitude and initiated descent via flight level change. Within 200 feet of beginning descent a red icon appeared on TCAS indicating an aircraft less than 1;000 feet below at 12 to 1 o'clock climbing toward us. TCAS issued an aural monitor vertical speed and indicated a level off. First Officer (Pilot Monitoring) advised ATC we were responding to a TCAS RA; and a level off was initiated. TCAS indicated conflict aircraft was 400 feet below and climbing toward us. I initiated a climb away from the conflict aircraft. TCAS continued to indicate conflict aircraft was climbing and maintaining a 400 feet separation while we were climbing until passing off our right side. While climbing in response to the RA; ATC issued instructions to climb to 35000 feet. After conflict aircraft passed we leveled off at 35000 feet. As conflict aircraft passed we identified it visually as an EMB175. TCAS conflicting aircraft icon disappeared from TCAS as the aircraft passed us. We resumed cruise flight at 35000 feet. Shortly after the resolution of the event ATC asked if we had received a TCAS RA. Several minutes prior to the event we had been instructed to descend from 37000 feet to 35000 feet. No traffic icons were displayed on the TCAS when issued instructions to descend to 34000 feet. The first indication of any aircraft in our vicinity was the pop up of the red icon. No progression from cyan to amber to red or an aural 'traffic' advisory. After the conflicting aircraft passed; the red icon just disappeared. No transition to amber or cyan. TCAS indicated the conflict aircraft was climbing throughout the event. Controller workload did not sound excessive and the only other aircraft on frequency did not have a similar call sign. We were in cruise flight and both I and the First Officer clearly heard the ATC instruction to descend to 34000 feet. The First Officer clearly repeated the instructions to ATC. I do not recall any frequency congestion as the instructions were issued and read back.

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.