Narrative:

Cleared the canuk arrival into atl. As we descended from altitude to cross canuk at 14000 ft; we were told to 'expect landing 8 left; fly the 8 left transition.' since we were arriving from the south; we had set up the FMS for a south landing. The first officer changed the runway to 8L; and selected the proper transition. As we crossed canuk; the first officer asked me what the bottom altitude on the chart was for the arrival; and I said 4000 ft and set 4000 ft in the altitude window. As we left 14000 ft for 12000 ft at the net point; we were given a frequency change. The controller was surprised that we were descending and had us stay at 12000 ft. Later on the arrival we were instructed to call center upon arrival at our gate. The rest of the approach and landing were uneventful. I called the operations manager at the number given; and we discussed the problem. No traffic separation problems were noted; and he just wanted to clarify the situation. The manager did explain the continuing problems they are experiencing with this arrival. I do know the difference between 'fly the transition' and 'descend on the transition.' as the captain; I am responsible; and I accept full responsibility; for the actions of my aircraft and crew. This will not happen again in my aircraft. I have two suggestions to help us with this arrival. 1) if there is any way to assign the transition earlier in the descent; it would cut down considerably in the cockpit workload. We were given this change as we leveled off at canuk; dealing with the resulting discontinuity in the FMS; and checking the points and altitudes against the paper chart. Managing all three issues at exactly the same time contributed to our confusion regarding the clearance. 2) if the controllers would state 'fly the 8L transition; maintain 14000 ft;' there would be no confusion. As we became task saturated when our workload increases; we remember the last number we hear. I am now convinced we would not have descended out of 14000 ft had these two words been added to the clearance. For my part; I will strive to never let cockpit workload get in the way of aircraft safety. In the future; I will clarify any questions I may have regarding a clearance.

Google
 

Original NASA ASRS Text

Title: B737 flight crew arriving ATL is cleared to fly the CANUK7 RNAV with the north transition; after having set up for the south transition. This last minute change and the required FMC work lead the crew to descend without clearance.

Narrative: Cleared the CANUK Arrival into ATL. As we descended from altitude to cross CANUK at 14000 FT; we were told to 'expect landing 8 left; fly the 8 left transition.' Since we were arriving from the south; we had set up the FMS for a south landing. The First Officer changed the runway to 8L; and selected the proper transition. As we crossed CANUK; the First Officer asked me what the bottom altitude on the chart was for the arrival; and I said 4000 FT and set 4000 FT in the altitude window. As we left 14000 FT for 12000 FT at the net point; we were given a frequency change. The Controller was surprised that we were descending and had us stay at 12000 FT. Later on the arrival we were instructed to call center upon arrival at our gate. The rest of the approach and landing were uneventful. I called the Operations Manager at the number given; and we discussed the problem. No traffic separation problems were noted; and he just wanted to clarify the situation. The manager did explain the continuing problems they are experiencing with this arrival. I do know the difference between 'fly the transition' and 'descend on the transition.' As the Captain; I am responsible; and I accept full responsibility; for the actions of my aircraft and crew. This will not happen again in my aircraft. I have two suggestions to help us with this arrival. 1) If there is any way to assign the transition earlier in the descent; it would cut down considerably in the cockpit workload. We were given this change as we leveled off at Canuk; dealing with the resulting discontinuity in the FMS; and checking the points and altitudes against the paper chart. Managing all three issues at exactly the same time contributed to our confusion regarding the clearance. 2) If the Controllers would state 'fly the 8L transition; maintain 14000 FT;' there would be no confusion. As we became task saturated when our workload increases; we remember the last number we hear. I am now convinced we would not have descended out of 14000 FT had these two words been added to the clearance. For my part; I will strive to never let cockpit workload get in the way of aircraft safety. In the future; I will clarify any questions I may have regarding a clearance.

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.