Narrative:

Descending from northwest to denver, approach said to descend and maintain 17,000'. After beginning descent, they said to reduce to 250 KTS. Then cleared to 12,000'. After beginning descent, approach said to reduce to 210 KTS. Then cleared to 11,000'. Then cleared to 10,000'. Then during descent, told us to reduce to 170 KTS. We also had traffic calls and frequency changes during this relatively short span of time from about 35 northwest of den to about 10 mi out. While descending to 10,000 and stabilizing at 170 KTS, approach said we had widebody transport traffic at 10 O'clock, 4 mi, going to 17R (same runway we were to expect). Then he said to disregard, that the traffic was 2 O'clock, not 10 O'clock. During all this congestive conversation and maneuvering, I heard altitude alert go off, and discovered I had descended through 10,000 (cleared altitude) to 9700'. Immediately stopped descent and proceeded to climb back to 10,000 and controller cleared us to 9000'. We called widebody transport traffic in sight and were cleared visual with uneventful landing. Discussion with captain later. He said he was more concerned with us watching outside for traffic rather than missing altitude a couple hundred feet. I suggest a change in VFR parallel runway approach procedures at den. The proximity of aircraft and frequency congestion make denver's procedures boarder of unsafe by being so demanding and distractive.

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Original NASA ASRS Text

Title: FO ON ACR MLG COMPLAINS OF ATC HANDLING WITH REGARD TO NUMEROUS SPEED CHANGES, FREQ SWITCHOVERS, AND INTERMEDIATE ALTS, ALL OF WHICH RESULTED IN ENOUGH DISTR TO CAUSE THE FO TO OVERSHOOT HIS ALT BY 300' ON DESCENT.

Narrative: DESCENDING FROM NW TO DENVER, APCH SAID TO DSND AND MAINTAIN 17,000'. AFTER BEGINNING DSCNT, THEY SAID TO REDUCE TO 250 KTS. THEN CLRED TO 12,000'. AFTER BEGINNING DSCNT, APCH SAID TO REDUCE TO 210 KTS. THEN CLRED TO 11,000'. THEN CLRED TO 10,000'. THEN DURING DSCNT, TOLD US TO REDUCE TO 170 KTS. WE ALSO HAD TFC CALLS AND FREQ CHANGES DURING THIS RELATIVELY SHORT SPAN OF TIME FROM ABOUT 35 NW OF DEN TO ABOUT 10 MI OUT. WHILE DESCENDING TO 10,000 AND STABILIZING AT 170 KTS, APCH SAID WE HAD WDB TFC AT 10 O'CLOCK, 4 MI, GOING TO 17R (SAME RWY WE WERE TO EXPECT). THEN HE SAID TO DISREGARD, THAT THE TFC WAS 2 O'CLOCK, NOT 10 O'CLOCK. DURING ALL THIS CONGESTIVE CONVERSATION AND MANEUVERING, I HEARD ALT ALERT GO OFF, AND DISCOVERED I HAD DESCENDED THROUGH 10,000 (CLRED ALT) TO 9700'. IMMEDIATELY STOPPED DSCNT AND PROCEEDED TO CLIMB BACK TO 10,000 AND CTLR CLRED US TO 9000'. WE CALLED WDB TFC IN SIGHT AND WERE CLRED VISUAL WITH UNEVENTFUL LNDG. DISCUSSION WITH CAPT LATER. HE SAID HE WAS MORE CONCERNED WITH US WATCHING OUTSIDE FOR TFC RATHER THAN MISSING ALT A COUPLE HUNDRED FEET. I SUGGEST A CHANGE IN VFR PARALLEL RWY APCH PROCS AT DEN. THE PROX OF ACFT AND FREQ CONGESTION MAKE DENVER'S PROCS BOARDER OF UNSAFE BY BEING SO DEMANDING AND DISTRACTIVE.

Data retrieved from NASA's ASRS site as of July 2007 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.