Narrative:

Our schedule flight from ord to lex. We were level on autoplt at our cruise altitude of FL250. Were at approximately 65 NM northwest of lex. I left the frequency to get ATIS. I returned and was given a descent clearance to FL230. The captain started the descent on autoplt. I started the cabin down and set the altitude preselect. We were then cleared to FL180. I again set the cabin and altitude preselect. We were then cleared to FL170 and given a heading of 090 degree for descent. The altitude preselect was again reset and I set the cabin at field elevation. We were now less then 50 NM from the field. The above took place in a matter of 1 to 2 minutes. Calls were being answered and orders carried out at about the maximum rate possible because of our short distance from the field we were descending at a high rate approximately 250 FPM. After the last call I proceeded to figure and set the landing data. While setting the N1 bugs the altitude alerter went off. I at first thought the captain had bumped the high speed warning then realizing the tone was not right I looked up to see us passing through 16600' climbing. Indy center called asking us our altitude. By the time he was done talking and I answered we were leveling at FL170 and I reported it as such indy called traffic at 12 O'clock 2 mi FL160' which we called in sight. Our aircraft then proceeded to land at lex uneventfully. Contributing factors: our altitude preselect performs 2 functions. You first select the altitude in the window then you press a button to arm the preselect function when on autoplt. Each change of altitude in window disarms the preselect. Was this button not pushed? I don't know. This function often times doesn't take on the first push also this autoplt often times doesn't level off when descending rapidly even when programmed to. Understand after each of the above radio calls I was trying to figure landing data but was interupted by the next call. I do not remember if I set the last altitude change or if the captain had to help me out. This would normally be my responsibility the (PNF) in our procedures but is sometimes shared when the PNF is rushed. Human performance factors: this trip started with a checkin of xa:55 am and wakeup call of xa:00 am. Upon arrival at the airport we were supposed to get a car and drive 30 minutes to another airport (atw to osh) to pickup our aircraft but the car was not there so we got a cabin attendant arriving in osh late. We then rushed through our checks, flew 4 legs, did an aircraft switch and proceeded to lex west/O a break or food. Both the captain and I discussed the fatigue we both felt while on the ground at ord before departing for lex and ways each of us used to fight it. We were in agreement that a nap was in order upon arrival, instead I'm writing this report. Corrective actions: I don't have any definitive answer but I don't know that the combination of fatigue, a rushed and interupted procedure is a formula for disaster. The sounding of the altitude alerter at 100-200' would have helped to minimize the deviation (instead of 300' now used). I must once again commit myself to check, rechk and check again. Callback conversation with reporter revealed the following: general discussion of the fatigue involved in the operation of commuter airlines.

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Original NASA ASRS Text

Title: ALTITUDE DEVIATION OVERSHOT.

Narrative: OUR SCHEDULE FLT FROM ORD TO LEX. WE WERE LEVEL ON AUTOPLT AT OUR CRUISE ALT OF FL250. WERE AT APPROX 65 NM NW OF LEX. I LEFT THE FREQ TO GET ATIS. I RETURNED AND WAS GIVEN A DSNT CLRNC TO FL230. THE CAPT STARTED THE DSNT ON AUTOPLT. I STARTED THE CABIN DOWN AND SET THE ALT PRESELECT. WE WERE THEN CLRED TO FL180. I AGAIN SET THE CABIN AND ALT PRESELECT. WE WERE THEN CLRED TO FL170 AND GIVEN A HDG OF 090 DEG FOR DSNT. THE ALT PRESELECT WAS AGAIN RESET AND I SET THE CABIN AT FIELD ELEVATION. WE WERE NOW LESS THEN 50 NM FROM THE FIELD. THE ABOVE TOOK PLACE IN A MATTER OF 1 TO 2 MINUTES. CALLS WERE BEING ANSWERED AND ORDERS CARRIED OUT AT ABOUT THE MAX RATE POSSIBLE BECAUSE OF OUR SHORT DISTANCE FROM THE FIELD WE WERE DSNDING AT A HIGH RATE APPROX 250 FPM. AFTER THE LAST CALL I PROCEEDED TO FIGURE AND SET THE LNDG DATA. WHILE SETTING THE N1 BUGS THE ALT ALERTER WENT OFF. I AT FIRST THOUGHT THE CAPT HAD BUMPED THE HIGH SPD WARNING THEN REALIZING THE TONE WAS NOT RIGHT I LOOKED UP TO SEE US PASSING THROUGH 16600' CLBING. INDY CTR CALLED ASKING US OUR ALT. BY THE TIME HE WAS DONE TALKING AND I ANSWERED WE WERE LEVELING AT FL170 AND I RPTED IT AS SUCH INDY CALLED TFC AT 12 O'CLOCK 2 MI FL160' WHICH WE CALLED IN SIGHT. OUR ACFT THEN PROCEEDED TO LAND AT LEX UNEVENTFULLY. CONTRIBUTING FACTORS: OUR ALT PRESELECT PERFORMS 2 FUNCTIONS. YOU FIRST SELECT THE ALT IN THE WINDOW THEN YOU PRESS A BUTTON TO ARM THE PRESELECT FUNCTION WHEN ON AUTOPLT. EACH CHANGE OF ALT IN WINDOW DISARMS THE PRESELECT. WAS THIS BUTTON NOT PUSHED? I DON'T KNOW. THIS FUNCTION OFTEN TIMES DOESN'T TAKE ON THE FIRST PUSH ALSO THIS AUTOPLT OFTEN TIMES DOESN'T LEVEL OFF WHEN DSNDING RAPIDLY EVEN WHEN PROGRAMMED TO. UNDERSTAND AFTER EACH OF THE ABOVE RADIO CALLS I WAS TRYING TO FIGURE LNDG DATA BUT WAS INTERUPTED BY THE NEXT CALL. I DO NOT REMEMBER IF I SET THE LAST ALT CHANGE OR IF THE CAPT HAD TO HELP ME OUT. THIS WOULD NORMALLY BE MY RESPONSIBILITY THE (PNF) IN OUR PROCS BUT IS SOMETIMES SHARED WHEN THE PNF IS RUSHED. HUMAN PERFORMANCE FACTORS: THIS TRIP STARTED WITH A CHECKIN OF XA:55 AM AND WAKEUP CALL OF XA:00 AM. UPON ARR AT THE ARPT WE WERE SUPPOSED TO GET A CAR AND DRIVE 30 MINUTES TO ANOTHER ARPT (ATW TO OSH) TO PICKUP OUR ACFT BUT THE CAR WAS NOT THERE SO WE GOT A CAB ARRIVING IN OSH LATE. WE THEN RUSHED THROUGH OUR CHKS, FLEW 4 LEGS, DID AN ACFT SWITCH AND PROCEEDED TO LEX W/O A BREAK OR FOOD. BOTH THE CAPT AND I DISCUSSED THE FATIGUE WE BOTH FELT WHILE ON THE GND AT ORD BEFORE DEPARTING FOR LEX AND WAYS EACH OF US USED TO FIGHT IT. WE WERE IN AGREEMENT THAT A NAP WAS IN ORDER UPON ARR, INSTEAD I'M WRITING THIS RPT. CORRECTIVE ACTIONS: I DON'T HAVE ANY DEFINITIVE ANSWER BUT I DON'T KNOW THAT THE COMBINATION OF FATIGUE, A RUSHED AND INTERUPTED PROC IS A FORMULA FOR DISASTER. THE SOUNDING OF THE ALT ALERTER AT 100-200' WOULD HAVE HELPED TO MINIMIZE THE DEV (INSTEAD OF 300' NOW USED). I MUST ONCE AGAIN COMMIT MYSELF TO CHK, RECHK AND CHK AGAIN. CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING: GENERAL DISCUSSION OF THE FATIGUE INVOLVED IN THE OPERATION OF COMMUTER AIRLINES.

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.