Narrative:

Somewhere around ood we were cleared to climb to what we both thought was FL280, which the captain set in the altitude window on the MCP. At the time, neither one of us noticed the discrepancy between the flight planned (270) altitude and what we were just given. It was about this time that I turned on the autoplt, utilizing both RNAV and VNAV functions. (I (first officer) was flying and the captain was handling the radios.) at FL270, the aircraft leveled itself off, because regardless of what is in the altitude window, it will not climb higher than the altitude loaded into the computer if you are utilizing the VNAV function. After about 2 seconds, I realized what had happened and pointed it out to the captain by gestures to the 2 readouts (280 and 270) and said '280, right?' he said 'yeah', and since I was so sure I heard us cleared to 280 previously, it didn't even cross my mind to doublechk with the controller. His 'yeah' was confirmation enough for me (I even remember thinking that I expected the controller to query us at any moment as to why we had leveled off at 270). So without any further hesitation, lest the controller 'holler' at us for leveling off 1000' too low, I reset the MCP to 280 and let the aircraft climb the last 1000'. After about 2 minutes, the controller said he showed us at FL280, and asked, 'is that correct?' the captain replied that it was. He then informed us that our clearance limit was FL270, not FL280. At his request, we immediately descended back down to FL270. At that point, he handed us over to ZNY. Fatigue: at the time of the occurrence, we had already been on duty for over 12 hours due to equipment problems. And as a result we were over 3 hours late. And we were both very tired. We had even discussed the possibility of telling the company that we were too tired to continue, even though we were legal, before we left dca. This is because the WX at bdl was right at CAT ii minimums, and neither one of us relished the thought of having to shoot a tight approach in our 'less than fully alert' condition. However, the dispatcher told the captain that the bdl WX was coming up and would probably be much better at our time of arrival. So, based on that information, we decided to continue. After the incident occurred, we discussed it and both of us thought that we heard 'FL280'. But since we were both very tired, we were sure it was our mistake and not the controller's. And for that reason, decided not to query him on the subject. Scheduling practices: this trip pairing had a duty day of 12 hours, 4 mins. Indeed, even on an on-time, VFR day, we would have been exhausted. But when you add WX and maintenance delays, it can become unbearable (and unsafe). And it is usually at these times that the company runs out of reserve pilots. So the impetus is for you to continue the trip.

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Original NASA ASRS Text

Title: FLT CREW OF MLG MISUNDERSTOOD CLRNC, CLIMBED TO FL280 INSTEAD OF CLEARED FL270.

Narrative: SOMEWHERE AROUND OOD WE WERE CLRED TO CLIMB TO WHAT WE BOTH THOUGHT WAS FL280, WHICH THE CAPT SET IN THE ALT WINDOW ON THE MCP. AT THE TIME, NEITHER ONE OF US NOTICED THE DISCREPANCY BETWEEN THE FLT PLANNED (270) ALT AND WHAT WE WERE JUST GIVEN. IT WAS ABOUT THIS TIME THAT I TURNED ON THE AUTOPLT, UTILIZING BOTH RNAV AND VNAV FUNCTIONS. (I (F/O) WAS FLYING AND THE CAPT WAS HANDLING THE RADIOS.) AT FL270, THE ACFT LEVELED ITSELF OFF, BECAUSE REGARDLESS OF WHAT IS IN THE ALT WINDOW, IT WILL NOT CLIMB HIGHER THAN THE ALT LOADED INTO THE COMPUTER IF YOU ARE UTILIZING THE VNAV FUNCTION. AFTER ABOUT 2 SECONDS, I REALIZED WHAT HAD HAPPENED AND POINTED IT OUT TO THE CAPT BY GESTURES TO THE 2 READOUTS (280 AND 270) AND SAID '280, RIGHT?' HE SAID 'YEAH', AND SINCE I WAS SO SURE I HEARD US CLRED TO 280 PREVIOUSLY, IT DIDN'T EVEN CROSS MY MIND TO DOUBLECHK WITH THE CTLR. HIS 'YEAH' WAS CONFIRMATION ENOUGH FOR ME (I EVEN REMEMBER THINKING THAT I EXPECTED THE CTLR TO QUERY US AT ANY MOMENT AS TO WHY WE HAD LEVELED OFF AT 270). SO WITHOUT ANY FURTHER HESITATION, LEST THE CTLR 'HOLLER' AT US FOR LEVELING OFF 1000' TOO LOW, I RESET THE MCP TO 280 AND LET THE ACFT CLIMB THE LAST 1000'. AFTER ABOUT 2 MINUTES, THE CTLR SAID HE SHOWED US AT FL280, AND ASKED, 'IS THAT CORRECT?' THE CAPT REPLIED THAT IT WAS. HE THEN INFORMED US THAT OUR CLRNC LIMIT WAS FL270, NOT FL280. AT HIS REQUEST, WE IMMEDIATELY DESCENDED BACK DOWN TO FL270. AT THAT POINT, HE HANDED US OVER TO ZNY. FATIGUE: AT THE TIME OF THE OCCURRENCE, WE HAD ALREADY BEEN ON DUTY FOR OVER 12 HRS DUE TO EQUIPMENT PROBLEMS. AND AS A RESULT WE WERE OVER 3 HRS LATE. AND WE WERE BOTH VERY TIRED. WE HAD EVEN DISCUSSED THE POSSIBILITY OF TELLING THE COMPANY THAT WE WERE TOO TIRED TO CONTINUE, EVEN THOUGH WE WERE LEGAL, BEFORE WE LEFT DCA. THIS IS BECAUSE THE WX AT BDL WAS RIGHT AT CAT II MINIMUMS, AND NEITHER ONE OF US RELISHED THE THOUGHT OF HAVING TO SHOOT A TIGHT APCH IN OUR 'LESS THAN FULLY ALERT' CONDITION. HOWEVER, THE DISPATCHER TOLD THE CAPT THAT THE BDL WX WAS COMING UP AND WOULD PROBABLY BE MUCH BETTER AT OUR TIME OF ARRIVAL. SO, BASED ON THAT INFO, WE DECIDED TO CONTINUE. AFTER THE INCIDENT OCCURRED, WE DISCUSSED IT AND BOTH OF US THOUGHT THAT WE HEARD 'FL280'. BUT SINCE WE WERE BOTH VERY TIRED, WE WERE SURE IT WAS OUR MISTAKE AND NOT THE CTLR'S. AND FOR THAT REASON, DECIDED NOT TO QUERY HIM ON THE SUBJECT. SCHEDULING PRACTICES: THIS TRIP PAIRING HAD A DUTY DAY OF 12 HRS, 4 MINS. INDEED, EVEN ON AN ON-TIME, VFR DAY, WE WOULD HAVE BEEN EXHAUSTED. BUT WHEN YOU ADD WX AND MAINT DELAYS, IT CAN BECOME UNBEARABLE (AND UNSAFE). AND IT IS USUALLY AT THESE TIMES THAT THE COMPANY RUNS OUT OF RESERVE PLTS. SO THE IMPETUS IS FOR YOU TO CONTINUE THE TRIP.

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.