Narrative:

Mco-rsw, departing mco at XA20. The reporter was flying the aircraft. Climbing through 10000 ft with clearance to 14000 ft, the first officer left the frequency to brief the passenger with the usual public relations speech and to report the off times to the company. While he was on the PA, the controller issued us 'one-eight-zero.' I read back '180' and changed the altitude preselect to FL180. When the first officer returned to the cockpit, I briefed him on the altitude change. As we climbed through 14000 ft, we were handed off to ZMA. I began to realize something was amiss. Before the handoff was effected, mco queried our altitude. The first officer replied that we were climbing to FL180. The controller said the 180 was a heading, not an altitude. I had already arrested the climb and commenced a descent to 14000 ft during this exchange. The first officer said something about a miscom. I added that I had read back, 'FL180.' the controller very curtly replied that I had read back, 'one-eight-zero.' I apologized. We maintained 14000 ft, and continued to rsw. There was no traffic conflict or TCASII alert. Needless to say, I was a little put out with myself. There are several factors contributing to this incident. The nonstandard phraseology used both by the controller and by me is obvious. Had the controller said, 'turn left to a heading of 180 degrees,' there would have been no mistaking the number for an altitude. Had I read back, 'climbing to FL180,' as I thought I had, the controller would have caught the miscom. Had the first officer still been on the radio or otherwise involved in the conversation, he probably would have questioned the ambiguity. Furthermore, had the controller noted that we had not changed course for the last 15-20 mi, he would have known that we misunderstood and corrected the situation before we exceeded 14000 ft. There is one other large factor at work here. With the amount of time I have spent flying around the orlando area, it should have instantly occurred to me that departure control does not own the airspace above 14000 ft. One contributing factor as to why that did not happen is that I was not talking to ATC prior to the clearance -- I was concentrating on flying the airplane. The clearance came almost immediately after the first officer told me that he was going to make the PA. When the clearance came, I had it in the back of my mind that we were already talking to center, because departure cannot clear us to FL180. It also seemed odd, because we do not usually go to FL180 on this leg, but then again, we do not have the overall traffic picture. When the handoff came to center, I instantly realized the error and began the correction. This convoluted and flawed thinking comes from only one thing -- fatigue. The trip we were assigned is legal per the FARS. The previous day was a bit arduous, with 6 legs scheduled to 7 hours 52 mins of flight time, and actually taken 8 hours 23 mins to complete. The duty period was 12 hours 30 mins. That notwithstanding, we had 13 hours of rest before commencing the next day. We were actually rested, and not tired in the sleepy sense. However, this is a 21 leg, 5 day assignment, and it mixes early and late legs. The type of fatigue I am referring to stems not from sleepiness, but from sheer saturation of repetition. At a certain point, all the legs blur together. If nothing exceptional is happening, such as WX or mechanical difficulties, the repetitiveness of the job creates a sluggishness of mind. The onset of this sluggishness is insidious, and no matter how efficient and well-ingrained one's habits are, is difficult to detect. It becomes readily apparent when an incident such as this occurs. It is my opinion that the only true solution to this problem is regulatory. The insidious nature of the onset of this type of fatigue makes it imperative that the system itself mitigate the effects if the goal of zero accidents/zero incidents is to be achieved. The flight/duty limits are geared towards long-haul rtes, and not multiple short-haul route structures. Duty limits are not even addressed. Circadian rhythms, understood and researched for the last 50 yrs, are not catered to. Duty limits must be written, cycles must be taken into account in the regulations, and day/night mixes should be limited. The unions cannot accomplish this. That solution is too limiting, anyway. The companies will not do it, nor should they. Their job is to maximize profits, and I think we all appreciate that. However, the wet computers on board the aircraft and in the system are not machines! In this instance, 3 wet computers failed due to a combination of circumstances. Despite our best efforts, the system abetted this failure. There is a solution, and we must implement it.

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Original NASA ASRS Text

Title: FATIGUED FLC OF CL65 EXPERIENCES DIFFICULTIES WITH HDG ALT CLRNC MISCOM FROM MCO DEP.

Narrative: MCO-RSW, DEPARTING MCO AT XA20. THE RPTR WAS FLYING THE ACFT. CLBING THROUGH 10000 FT WITH CLRNC TO 14000 FT, THE FO LEFT THE FREQ TO BRIEF THE PAX WITH THE USUAL PUBLIC RELATIONS SPEECH AND TO RPT THE OFF TIMES TO THE COMPANY. WHILE HE WAS ON THE PA, THE CTLR ISSUED US 'ONE-EIGHT-ZERO.' I READ BACK '180' AND CHANGED THE ALT PRESELECT TO FL180. WHEN THE FO RETURNED TO THE COCKPIT, I BRIEFED HIM ON THE ALT CHANGE. AS WE CLBED THROUGH 14000 FT, WE WERE HANDED OFF TO ZMA. I BEGAN TO REALIZE SOMETHING WAS AMISS. BEFORE THE HDOF WAS EFFECTED, MCO QUERIED OUR ALT. THE FO REPLIED THAT WE WERE CLBING TO FL180. THE CTLR SAID THE 180 WAS A HDG, NOT AN ALT. I HAD ALREADY ARRESTED THE CLB AND COMMENCED A DSCNT TO 14000 FT DURING THIS EXCHANGE. THE FO SAID SOMETHING ABOUT A MISCOM. I ADDED THAT I HAD READ BACK, 'FL180.' THE CTLR VERY CURTLY REPLIED THAT I HAD READ BACK, 'ONE-EIGHT-ZERO.' I APOLOGIZED. WE MAINTAINED 14000 FT, AND CONTINUED TO RSW. THERE WAS NO TFC CONFLICT OR TCASII ALERT. NEEDLESS TO SAY, I WAS A LITTLE PUT OUT WITH MYSELF. THERE ARE SEVERAL FACTORS CONTRIBUTING TO THIS INCIDENT. THE NONSTANDARD PHRASEOLOGY USED BOTH BY THE CTLR AND BY ME IS OBVIOUS. HAD THE CTLR SAID, 'TURN L TO A HDG OF 180 DEGS,' THERE WOULD HAVE BEEN NO MISTAKING THE NUMBER FOR AN ALT. HAD I READ BACK, 'CLBING TO FL180,' AS I THOUGHT I HAD, THE CTLR WOULD HAVE CAUGHT THE MISCOM. HAD THE FO STILL BEEN ON THE RADIO OR OTHERWISE INVOLVED IN THE CONVERSATION, HE PROBABLY WOULD HAVE QUESTIONED THE AMBIGUITY. FURTHERMORE, HAD THE CTLR NOTED THAT WE HAD NOT CHANGED COURSE FOR THE LAST 15-20 MI, HE WOULD HAVE KNOWN THAT WE MISUNDERSTOOD AND CORRECTED THE SIT BEFORE WE EXCEEDED 14000 FT. THERE IS ONE OTHER LARGE FACTOR AT WORK HERE. WITH THE AMOUNT OF TIME I HAVE SPENT FLYING AROUND THE ORLANDO AREA, IT SHOULD HAVE INSTANTLY OCCURRED TO ME THAT DEP CTL DOES NOT OWN THE AIRSPACE ABOVE 14000 FT. ONE CONTRIBUTING FACTOR AS TO WHY THAT DID NOT HAPPEN IS THAT I WAS NOT TALKING TO ATC PRIOR TO THE CLRNC -- I WAS CONCENTRATING ON FLYING THE AIRPLANE. THE CLRNC CAME ALMOST IMMEDIATELY AFTER THE FO TOLD ME THAT HE WAS GOING TO MAKE THE PA. WHEN THE CLRNC CAME, I HAD IT IN THE BACK OF MY MIND THAT WE WERE ALREADY TALKING TO CTR, BECAUSE DEP CANNOT CLR US TO FL180. IT ALSO SEEMED ODD, BECAUSE WE DO NOT USUALLY GO TO FL180 ON THIS LEG, BUT THEN AGAIN, WE DO NOT HAVE THE OVERALL TFC PICTURE. WHEN THE HDOF CAME TO CTR, I INSTANTLY REALIZED THE ERROR AND BEGAN THE CORRECTION. THIS CONVOLUTED AND FLAWED THINKING COMES FROM ONLY ONE THING -- FATIGUE. THE TRIP WE WERE ASSIGNED IS LEGAL PER THE FARS. THE PREVIOUS DAY WAS A BIT ARDUOUS, WITH 6 LEGS SCHEDULED TO 7 HRS 52 MINS OF FLT TIME, AND ACTUALLY TAKEN 8 HRS 23 MINS TO COMPLETE. THE DUTY PERIOD WAS 12 HRS 30 MINS. THAT NOTWITHSTANDING, WE HAD 13 HRS OF REST BEFORE COMMENCING THE NEXT DAY. WE WERE ACTUALLY RESTED, AND NOT TIRED IN THE SLEEPY SENSE. HOWEVER, THIS IS A 21 LEG, 5 DAY ASSIGNMENT, AND IT MIXES EARLY AND LATE LEGS. THE TYPE OF FATIGUE I AM REFERRING TO STEMS NOT FROM SLEEPINESS, BUT FROM SHEER SATURATION OF REPETITION. AT A CERTAIN POINT, ALL THE LEGS BLUR TOGETHER. IF NOTHING EXCEPTIONAL IS HAPPENING, SUCH AS WX OR MECHANICAL DIFFICULTIES, THE REPETITIVENESS OF THE JOB CREATES A SLUGGISHNESS OF MIND. THE ONSET OF THIS SLUGGISHNESS IS INSIDIOUS, AND NO MATTER HOW EFFICIENT AND WELL-INGRAINED ONE'S HABITS ARE, IS DIFFICULT TO DETECT. IT BECOMES READILY APPARENT WHEN AN INCIDENT SUCH AS THIS OCCURS. IT IS MY OPINION THAT THE ONLY TRUE SOLUTION TO THIS PROB IS REGULATORY. THE INSIDIOUS NATURE OF THE ONSET OF THIS TYPE OF FATIGUE MAKES IT IMPERATIVE THAT THE SYS ITSELF MITIGATE THE EFFECTS IF THE GOAL OF ZERO ACCIDENTS/ZERO INCIDENTS IS TO BE ACHIEVED. THE FLT/DUTY LIMITS ARE GEARED TOWARDS LONG-HAUL RTES, AND NOT MULTIPLE SHORT-HAUL RTE STRUCTURES. DUTY LIMITS ARE NOT EVEN ADDRESSED. CIRCADIAN RHYTHMS, UNDERSTOOD AND RESEARCHED FOR THE LAST 50 YRS, ARE NOT CATERED TO. DUTY LIMITS MUST BE WRITTEN, CYCLES MUST BE TAKEN INTO ACCOUNT IN THE REGS, AND DAY/NIGHT MIXES SHOULD BE LIMITED. THE UNIONS CANNOT ACCOMPLISH THIS. THAT SOLUTION IS TOO LIMITING, ANYWAY. THE COMPANIES WILL NOT DO IT, NOR SHOULD THEY. THEIR JOB IS TO MAXIMIZE PROFITS, AND I THINK WE ALL APPRECIATE THAT. HOWEVER, THE WET COMPUTERS ON BOARD THE ACFT AND IN THE SYS ARE NOT MACHINES! IN THIS INSTANCE, 3 WET COMPUTERS FAILED DUE TO A COMBINATION OF CIRCUMSTANCES. DESPITE OUR BEST EFFORTS, THE SYS ABETTED THIS FAILURE. THERE IS A SOLUTION, AND WE MUST IMPLEMENT IT.

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.