Narrative:

Cleared to cross kaddy at 12;000 and then descend via the tyssn two RNAV arrival. VNAV was selected with an assigned 250 KT speed in the descent. Eight thousand ft was the selected altitude in the window for the VNAV descent. Center then issued a clearance to fly normal speed until kaddy. I wanted to pick up speed but knew that I would have to get below the depicted glide in order to slow for the 250 KT restriction at kaddy. So without saying a word to the first officer; I de-selected VNAV and selected vertical descent on the MCP while de-selecting the autothrottle. I descended below the glide and accelerated to about 275 and held that speed as we continued descent towards kaddy. I did not remember to place 12;000 ft in the altitude window. We noticed ice on the wings so I turned on the wing anti-ice and watched as the ice melted off the wings. As I turned off the wing ant-ice; the first officer noticed I was not leveling off at 12;000 ft as the kaddy restriction requires and he stopped the descent. I was surprised I missed seeing us descending through our altitude and quickly climbed the aircraft back to 12;000 ft. We flew through the altitude by about 500 ft. The rest of the flight continued without further incident. I made several mistakes. The first was that I made an MCP change and did not mention it to the first officer. Second; I did not remember to replace the altitude alerter to the next restriction altitude as required when de-selecting VNAV. Third; I allowed myself to be distracted at a critical time when I should have had my attention on flying the aircraft. I need to remember that anytime VNAV is deselected; or any other change; I should announce what action is being taken and immediately reselect the next altitude restriction in the window and fly the airplane.

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Original NASA ASRS Text

Title: A desire to meet ATC crossing restrictions and a failure to inform the other pilot of changes in the FMS configuration to do so; resulted in a failure to meet a 12;000 MSL crossing restriction at KADDY for a B737 flight crew.

Narrative: Cleared to cross KADDY at 12;000 and then descend via the TYSSN TWO RNAV Arrival. VNAV was selected with an assigned 250 KT speed in the descent. Eight thousand FT was the selected altitude in the window for the VNAV descent. Center then issued a clearance to fly normal speed until KADDY. I wanted to pick up speed but knew that I would have to get below the depicted glide in order to slow for the 250 KT restriction at KADDY. So without saying a word to the First Officer; I de-selected VNAV and selected vertical descent on the MCP while de-selecting the autothrottle. I descended below the glide and accelerated to about 275 and held that speed as we continued descent towards KADDY. I did not remember to place 12;000 FT in the altitude window. We noticed ice on the wings so I turned on the wing anti-ice and watched as the ice melted off the wings. As I turned off the wing ant-ice; the First Officer noticed I was not leveling off at 12;000 FT as the KADDY restriction requires and he stopped the descent. I was surprised I missed seeing us descending through our altitude and quickly climbed the aircraft back to 12;000 FT. We flew through the altitude by about 500 FT. The rest of the flight continued without further incident. I made several mistakes. The first was that I made an MCP change and did not mention it to the First Officer. Second; I did not remember to replace the altitude alerter to the next restriction altitude as required when de-selecting VNAV. Third; I allowed myself to be distracted at a critical time when I should have had my attention on flying the aircraft. I need to remember that anytime VNAV is deselected; or any other change; I should announce what action is being taken and immediately reselect the next altitude restriction in the window AND FLY THE AIRPLANE.

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.