Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 201; Flight Crew Total 14500; Flight Crew Type 2073
Communication Breakdown; Confusion
ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Issued New Clearance; Flight Crew FLC Overrode Automation; Flight Crew Took Evasive Action
Human Factors
During a bio-break with the Captain out in the Lavatory. While at cruise at 35;000 ATC called and requested that we slow to Mach .76. At that same time; we encountered moderate turbulence. While reading back the Mach .76 call; I requested lower to smooth air. ATC then said that it was smooth at 31;000 but to descend to 33;000 for now. I started descending to 33;000 via level change. When descending through 33;500 ATC then asked if we were on frequency. I replied that we were and he had literally just slowed us and cleared us to descend to 33;000. At that point; the controller said to maintain 35;000 and turn right 20 degrees. I started a climb back to 35;000 and a turn. Realizing the situation and that the automation was not moving fast enough; I clicked off the autopilot and auto thrust and turned and climbed back to 35;000. Once level; ATC seemed confused about the clearance but fortunately we had an additional pilot in the jump seat and we all clearly heard the clearance and call sign. I told ATC that fact and he was extremely apologetic realizing what had happened. During the event; both the jump seater and I noticed on the TCAS that we were within 100 feet of the other aircrafts altitude! At that point; we did not have the other aircraft in sight but shortly after; a [aircraft] went under our nose and left wing. Once clear of traffic; ATC then cleared us lower again and handed us off to the next controller. He again apologized and thanked us for our help. The end result is that we did not get a TCAS RA; but it was a close encounter. I believe had I left the automation on; it would have resulted in a RA or even worse! I also believe that [the other aircraft] did not get an RA either based on the fact that nothing was said about it on ATC.
Air carrier First Officer reported receiving a clearance from ATC that created an airborne conflict. ATC identified the error and issued a new instruction to deconflict.