Narrative:

We were departing grr runway 8R. Departure WX was light rain, 700 ft overcast and a temperature of 32 degrees F. Radar on takeoff showed some areas of more intense precipitation. Icing was anticipated and encountered during the climb out. Shortly after takeoff while performing the after takeoff checklist and starting airfoil anti-ice, we were issued a right turn to 170 degrees direct to fwa when able and apparently we were cleared to climb to 10000 ft. The altitude clearance was misunderstood and 17000 ft was set in the altitude window, and stated in the readback. The error was not caught until the first officer felt that 17000 ft was unusual and called to confirm the altitude as we were climbing through 12000 ft. We were informed that 10000 ft was the clearance altitude. I disconnected the autoplt and initiated an immediate descent. Altitude at this point was 13000 ft. Before we could descend back to 10000 ft, the departure controller got FL230 for us and we were handed off to ZAU. There was no traffic conflict, the climb was resumed and no further problems were encountered. I feel that the error was caused by the crew having to divide attention between the aircraft (checklist, anti- ice, and performance), the WX (icing, temperature inversion, continuous light turbulence), and ATC (departure and en route clrncs). In fact the anti-ice was instituted twice during the first 10000 ft of climb out. The first time was in conjunction with the after takeoff checklist at 3000 ft then it was all secured at approximately 6000 ft due to increasing ram air temperature, and then re-instituted at 10000 ft due to decreasing ram air temperature at that point. I think the 170 degree heading that was issued was mistakenly accepted and read back as 17000 ft. This occurred during the after takeoff checklist. Supplemental information from acn 332990: cockpit very busy on climb out. First officer busy with monitoring aircraft performance, aircraft icing for wing and engine, completing after takeoff checklist, observing radar, and handling communications. No response from controller regarding incorrect altitude readback. No correction from departure control only reaffirmed that I had understood the clearance.

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Original NASA ASRS Text

Title: AN ALT ASSIGNMENT WAS OVERSHOT WHEN A FLC READ BACK THE WRONG ALT CLRNC DURING DEP IN WX AND ICING CONDITIONS. BOTH CREW MEMBERS RPT THAT THE DIVISION OF ATTN BTWN TOO MANY TASKS AND DISTR WITH THE USE OF ACFT ANTI-ICE PROCS WERE THE MAIN CAUSAL FACTORS. READBACK HEARBACK PROBS CONTRIBUTED.

Narrative: WE WERE DEPARTING GRR RWY 8R. DEP WX WAS LIGHT RAIN, 700 FT OVCST AND A TEMP OF 32 DEGS F. RADAR ON TKOF SHOWED SOME AREAS OF MORE INTENSE PRECIP. ICING WAS ANTICIPATED AND ENCOUNTERED DURING THE CLBOUT. SHORTLY AFTER TKOF WHILE PERFORMING THE AFTER TKOF CHKLIST AND STARTING AIRFOIL ANTI-ICE, WE WERE ISSUED A R TURN TO 170 DEGS DIRECT TO FWA WHEN ABLE AND APPARENTLY WE WERE CLRED TO CLB TO 10000 FT. THE ALT CLRNC WAS MISUNDERSTOOD AND 17000 FT WAS SET IN THE ALT WINDOW, AND STATED IN THE READBACK. THE ERROR WAS NOT CAUGHT UNTIL THE FO FELT THAT 17000 FT WAS UNUSUAL AND CALLED TO CONFIRM THE ALT AS WE WERE CLBING THROUGH 12000 FT. WE WERE INFORMED THAT 10000 FT WAS THE CLRNC ALT. I DISCONNECTED THE AUTOPLT AND INITIATED AN IMMEDIATE DSCNT. ALT AT THIS POINT WAS 13000 FT. BEFORE WE COULD DSND BACK TO 10000 FT, THE DEP CTLR GOT FL230 FOR US AND WE WERE HANDED OFF TO ZAU. THERE WAS NO TFC CONFLICT, THE CLB WAS RESUMED AND NO FURTHER PROBS WERE ENCOUNTERED. I FEEL THAT THE ERROR WAS CAUSED BY THE CREW HAVING TO DIVIDE ATTN BTWN THE ACFT (CHKLIST, ANTI- ICE, AND PERFORMANCE), THE WX (ICING, TEMP INVERSION, CONTINUOUS LIGHT TURB), AND ATC (DEP AND ENRTE CLRNCS). IN FACT THE ANTI-ICE WAS INSTITUTED TWICE DURING THE FIRST 10000 FT OF CLBOUT. THE FIRST TIME WAS IN CONJUNCTION WITH THE AFTER TKOF CHKLIST AT 3000 FT THEN IT WAS ALL SECURED AT APPROX 6000 FT DUE TO INCREASING RAM AIR TEMP, AND THEN RE-INSTITUTED AT 10000 FT DUE TO DECREASING RAM AIR TEMP AT THAT POINT. I THINK THE 170 DEG HDG THAT WAS ISSUED WAS MISTAKENLY ACCEPTED AND READ BACK AS 17000 FT. THIS OCCURRED DURING THE AFTER TKOF CHKLIST. SUPPLEMENTAL INFO FROM ACN 332990: COCKPIT VERY BUSY ON CLBOUT. FO BUSY WITH MONITORING ACFT PERFORMANCE, ACFT ICING FOR WING AND ENG, COMPLETING AFTER TKOF CHKLIST, OBSERVING RADAR, AND HANDLING COMS. NO RESPONSE FROM CTLR REGARDING INCORRECT ALT READBACK. NO CORRECTION FROM DEP CTL ONLY REAFFIRMED THAT I HAD UNDERSTOOD THE CLRNC.

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.