Large Transport
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 243; Flight Crew Type 10000
Distraction; Confusion; Communication Breakdown; Situational Awareness
ATC Issue All Types; Conflict Airborne Conflict; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Provided Assistance; Flight Crew Returned To Clearance
Human Factors; Procedure
Climbing out of DEN on the SPAZZ Departure off Runway 17R; climb via except maintain 10;000 ft. Hand flying. Approaching 10;000 ft; Controller gave us direct SPAZZ. Turned the aircraft and then Controller called traffic one o'clock; ten miles; I thought I heard him say 'out of 11'. I thought it odd that he'd turn us towards a descending aircraft and proceeded to slow the climb. As we looked for traffic I made a remark to the FO that I 'didn't like this'.  As we were looking for traffic I may have climbed slightly above 10;000 ft. Controller then said '(call sign) verify you're climbing to 11;000 ft.' Thinking I'd screwed up; I immediately raised the nose and started the aircraft towards 11 when the Controller corrected himself and said '10;000 ft'.  At that time we were about 10;350 ft.  FO and I looked at each other and there was an immediate discussion about what we were cleared to since the next waypoint we would've had was RAYDR; which is at or below 10;000 ft but once turned off the SID that shouldn't have applied. The aircraft was headed back down to 10;000 ft when we acquired and called the traffic. Controller then gave us a turn to 120 degrees. Started the turn and Controller then gave the 'possible pilot deviation call this number'. When we got to [our destination] we called. ATC said the Controller's instruction was 'direct SPAZZ; maintain 10;000 ft.' Neither of us recalled hearing the 'maintain 10;000 ft' and PM responded with 'direct SPAZZ' with no altitude mentioned. They also claimed we'd not leveled off at 10;000 ft and got as high as 10;500 ft; and that we were at 10;300 ft when the Controller queried us. They did acknowledge that the Controller did say 11;000 ft at first and then corrected himself. They said that since we had the aircraft in sight; there wasn't a conflict but they would have to pass it up for review and would get back with us. I believe this was more of a Controller error because when he asked us to verify we were climbing to 11;000 ft set the stage for the confusion that followed.
Pilot reports of a confusing transmission and instruction to climb to a different altitude then assigned and then descend back to the previously assigned altitude.