Narrative:

We took off from cle airport runway 36. Our takeoff clearance was runway heading. Our pretaxi clearance was cle 6 departure, maintain 5000', expect 9000' 10 mins after departure. We were handed over to departure control from tower. Departure assigned 'approximately' heading 090 degrees, maintain 5000'. I read back clearance and requested higher. Departure said higher wasn't available yet due to traffic at 11 O'clock. We were approximately 4800' at this time. Captain was about to level at 5000' when departure then assigned heading 210 degrees and climb to 6000'. I read back the clearance, told the captain '1000' to go,' and I then set 6000' in our ADF window (we sometimes use this as a makeshift altitude alert, if one isn't available). Captain proceeded to climb. I told him I'd be off the frequency to talk to company for a few seconds. While talking to company, the captain asked me if we were 'only' clrd to 6000'. I confirmed 6000' was our final for now. I checked back in with captain after talking to company. I told him I was having trouble with my headset. It was cutting out. About 30 seconds later the captain asked, 'was our altitude assigned 6000'?' we were already at approximately 6700'. 1 second later ATC asked what our assigned altitude was by departure control. I responded 6000'. The captain proceeded to change selection on transponder from 'altitude' to 'on'. He began descent to 6000'. The controller said he lost our mode C and questioned our altitude. I asked the captain, 'do you want me to tell him the truth? What should I say?' he said he's got it and acknowledged being at 6000'. Being as we didn't tell the truth and I wasn't sure what the captain was up to, I indicated I wasn't going to talk to ATC now. At this point the captain handled the rest of the radio communication between ATC and us. ATC asked us our destination and asked us to copy his phone # and call upon arrival. The captain copied the # and acknowledged he'd call when on the ground. Contributing factors: no altitude alert, distraction--my headset cutting out. Frame of mind--we started the day early am, flew 1 leg (35 mins), sat on ground for approximately 7 hours waiting for aircraft to come available, flight cancelled throughout day due to aircraft availability. I think that long of a break in a day breaks up your concentration. Fatigue.

Related reports:

Google
 

Original NASA ASRS Text

Title: COMMUTER SMA ALT DEVIATION OVERSHOT DURING CLIMB THEN TURNED TRANSPONDER OFF TO TRY AND COVER ERROR.

Narrative: WE TOOK OFF FROM CLE ARPT RWY 36. OUR TKOF CLRNC WAS RWY HDG. OUR PRETAXI CLRNC WAS CLE 6 DEP, MAINTAIN 5000', EXPECT 9000' 10 MINS AFTER DEP. WE WERE HANDED OVER TO DEP CTL FROM TWR. DEP ASSIGNED 'APPROX' HDG 090 DEGS, MAINTAIN 5000'. I READ BACK CLRNC AND REQUESTED HIGHER. DEP SAID HIGHER WASN'T AVAILABLE YET DUE TO TFC AT 11 O'CLOCK. WE WERE APPROX 4800' AT THIS TIME. CAPT WAS ABOUT TO LEVEL AT 5000' WHEN DEP THEN ASSIGNED HDG 210 DEGS AND CLB TO 6000'. I READ BACK THE CLRNC, TOLD THE CAPT '1000' TO GO,' AND I THEN SET 6000' IN OUR ADF WINDOW (WE SOMETIMES USE THIS AS A MAKESHIFT ALT ALERT, IF ONE ISN'T AVAILABLE). CAPT PROCEEDED TO CLB. I TOLD HIM I'D BE OFF THE FREQ TO TALK TO COMPANY FOR A FEW SECS. WHILE TALKING TO COMPANY, THE CAPT ASKED ME IF WE WERE 'ONLY' CLRD TO 6000'. I CONFIRMED 6000' WAS OUR FINAL FOR NOW. I CHKED BACK IN WITH CAPT AFTER TALKING TO COMPANY. I TOLD HIM I WAS HAVING TROUBLE WITH MY HEADSET. IT WAS CUTTING OUT. ABOUT 30 SECS LATER THE CAPT ASKED, 'WAS OUR ALT ASSIGNED 6000'?' WE WERE ALREADY AT APPROX 6700'. 1 SEC LATER ATC ASKED WHAT OUR ASSIGNED ALT WAS BY DEP CTL. I RESPONDED 6000'. THE CAPT PROCEEDED TO CHANGE SELECTION ON TRANSPONDER FROM 'ALT' TO 'ON'. HE BEGAN DSCNT TO 6000'. THE CTLR SAID HE LOST OUR MODE C AND QUESTIONED OUR ALT. I ASKED THE CAPT, 'DO YOU WANT ME TO TELL HIM THE TRUTH? WHAT SHOULD I SAY?' HE SAID HE'S GOT IT AND ACKNOWLEDGED BEING AT 6000'. BEING AS WE DIDN'T TELL THE TRUTH AND I WASN'T SURE WHAT THE CAPT WAS UP TO, I INDICATED I WASN'T GOING TO TALK TO ATC NOW. AT THIS POINT THE CAPT HANDLED THE REST OF THE RADIO COM BTWN ATC AND US. ATC ASKED US OUR DEST AND ASKED US TO COPY HIS PHONE # AND CALL UPON ARR. THE CAPT COPIED THE # AND ACKNOWLEDGED HE'D CALL WHEN ON THE GND. CONTRIBUTING FACTORS: NO ALT ALERT, DISTR--MY HEADSET CUTTING OUT. FRAME OF MIND--WE STARTED THE DAY EARLY AM, FLEW 1 LEG (35 MINS), SAT ON GND FOR APPROX 7 HRS WAITING FOR ACFT TO COME AVAILABLE, FLT CANCELLED THROUGHOUT DAY DUE TO ACFT AVAILABILITY. I THINK THAT LONG OF A BREAK IN A DAY BREAKS UP YOUR CONCENTRATION. FATIGUE.

Data retrieved from NASA's ASRS site as of August 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.