Narrative:

We were cleared to descend via the PURRL2 RNAV STAR into den and were told to expect runway 35R. As the pilot monitoring; I set 9;000 feet in the altitude window and the pilot flying engaged the managed descent mode and we started our descent. Just prior to crossing the waypoint dandd; the pilot flying was entering data into the secondary flight plan in the hopes that we would be approved to land on runway 35L. He accidentally activated the secondary flight plan which dumped the PURRL2 STAR and the airplane failed to make the required turn at dandd. Also; because the altitude window still had 9;000 feet the airplane continued to descend. The pilot flying is very new to the airbus (still a high minutes captain) and he struggled to identify what had just happened. He was attempting to re-load the arrival into the FMC when I noticed what was going on and asked him what happened. He replied that he didn't know what happened but I could see that the RNAV arrival was no longer loaded in the FMC and that the airplane was no longer flying the PURRL2 as we had been cleared. I took over FMC programming duties as the captain placed the airplane in heading mode in an effort to return us to the course but ATC called us stating that we were 2 miles north of course. By this time; the PURRL2 arrival had been successfully re-loaded into the FMC but we failed to identify that the airplane was still descending below the constraint on the arrival. Once again; ATC called to state that we were below the required altitude and they vectored us off of the arrival giving us a heading and altitude to fly. The entire deviation lasted approximately two minutes but enough time to fail to make a required turn and fail to level off at the correct altitude. The remainder of the arrival to runway 35R was uneventful.

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Original NASA ASRS Text

Title: A320 First Officer reported track and altitude deviations occurred on the PURRL2 RNAV arrival into DEN when the FMC was accidentally mis-programmed.

Narrative: We were cleared to descend via the PURRL2 RNAV STAR into DEN and were told to expect Runway 35R. As the pilot monitoring; I set 9;000 feet in the altitude window and the pilot flying engaged the managed descent mode and we started our descent. Just prior to crossing the waypoint DANDD; the pilot flying was entering data into the secondary flight plan in the hopes that we would be approved to land on Runway 35L. He accidentally activated the secondary flight plan which dumped the PURRL2 STAR and the airplane failed to make the required turn at DANDD. Also; because the altitude window still had 9;000 feet the airplane continued to descend. The pilot flying is very new to the Airbus (still a high minutes Captain) and he struggled to identify what had just happened. He was attempting to re-load the arrival into the FMC when I noticed what was going on and asked him what happened. He replied that he didn't know what happened but I could see that the RNAV arrival was no longer loaded in the FMC and that the airplane was no longer flying the PURRL2 as we had been cleared. I took over FMC programming duties as the Captain placed the airplane in heading mode in an effort to return us to the course but ATC called us stating that we were 2 miles north of course. By this time; the PURRL2 Arrival had been successfully re-loaded into the FMC but we failed to identify that the airplane was still descending below the constraint on the arrival. Once again; ATC called to state that we were below the required altitude and they vectored us off of the arrival giving us a heading and altitude to fly. The entire deviation lasted approximately two minutes but enough time to fail to make a required turn and fail to level off at the correct altitude. The remainder of the arrival to Runway 35R was uneventful.

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.