Narrative:

We were level at 12000 ft in the vicinity of wilmington, oh, in contact with ZID. It was early morning and traffic was light. I was observing flight operations in training for a part 135 freight hauler. Nearing louisville, ky, I realized that no radio calls had been made to our aircraft in quite some time, perhaps over an hour. In fact, I could now only hear aircraft transmitting to ATC, and not ATC's xmissions. I knew we must have left center's airspace. We neither heard nor replied to any handoffs. When I brought this up to the first officer, he agreed there was a problem and began attempting to contact ATC. After several tries on different frequencys, we reached nashville ATC, who said that ATC had been attempting to contact us for over an hour. They said we had flown through cvg approach airspace without contacting them and that aircraft had been vectored around us. We saw no aircraft that would present a collision conflict at any time. The second identical event occurred on the dead head leg home to yip from bna. I was in the right seat, as PF, undergoing training on the part 91 leg of the flight. It was about XA30, in contact with dayton approach, when I again realized that no contact had been made with us in quite some time and that we must be at the limits of dayton approach's airspace, I brought this up to the captain who agreed. I contacted day approach, who said we should be with ZOB. Upon contacting center, they told us they had been attempting to contact us for a long time. Again, we heard nor replied to any ATC handoffs. The flight ended uneventfully, and I do not know if any aircraft were vectored around us. I do not feel the aircraft's radios malfunctioned, as they worked fine during all known xmissions and receptions, and no complaints had been made by any parties about our radios. I believe in both instances, ATC forgot about us and did not hand us off. Another major contributing factor was fatigue. All 3 of us were very tired and had been awake for over 24 hours straight. This fatigue slowed our recognition that we should be talking with someone else. Although we were dead-tired, I do not believe we missed handoffs in either instance. I have considered the possibility that we all fell asleep due to over-fatigue, but our airplane has no autoplt and needs fairly constant attention to altitude and course. We were level at our assigned altitude and on course at all times. Callback conversation with reporter revealed the following information: the reporter is flying the casa 212. He has not heard that the aircraft has had any problems with its radios. He is trying to be more aware of the ATC situation by asking for altimeter settings 'every 20 mins or so.' the FAA did not contact the crew regarding this incident. He now understands that part 135 air freight taxi operations are regularly very fatiguing, and fatigue is standard for the industry.

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Original NASA ASRS Text

Title: AN AIR TAXI FREIGHTER ACFT LOST COM ENRTE.

Narrative: WE WERE LEVEL AT 12000 FT IN THE VICINITY OF WILMINGTON, OH, IN CONTACT WITH ZID. IT WAS EARLY MORNING AND TFC WAS LIGHT. I WAS OBSERVING FLT OPS IN TRAINING FOR A PART 135 FREIGHT HAULER. NEARING LOUISVILLE, KY, I REALIZED THAT NO RADIO CALLS HAD BEEN MADE TO OUR ACFT IN QUITE SOME TIME, PERHAPS OVER AN HR. IN FACT, I COULD NOW ONLY HEAR ACFT XMITTING TO ATC, AND NOT ATC'S XMISSIONS. I KNEW WE MUST HAVE LEFT CTR'S AIRSPACE. WE NEITHER HEARD NOR REPLIED TO ANY HDOFS. WHEN I BROUGHT THIS UP TO THE FO, HE AGREED THERE WAS A PROB AND BEGAN ATTEMPTING TO CONTACT ATC. AFTER SEVERAL TRIES ON DIFFERENT FREQS, WE REACHED NASHVILLE ATC, WHO SAID THAT ATC HAD BEEN ATTEMPTING TO CONTACT US FOR OVER AN HR. THEY SAID WE HAD FLOWN THROUGH CVG APCH AIRSPACE WITHOUT CONTACTING THEM AND THAT ACFT HAD BEEN VECTORED AROUND US. WE SAW NO ACFT THAT WOULD PRESENT A COLLISION CONFLICT AT ANY TIME. THE SECOND IDENTICAL EVENT OCCURRED ON THE DEAD HEAD LEG HOME TO YIP FROM BNA. I WAS IN THE R SEAT, AS PF, UNDERGOING TRAINING ON THE PART 91 LEG OF THE FLT. IT WAS ABOUT XA30, IN CONTACT WITH DAYTON APCH, WHEN I AGAIN REALIZED THAT NO CONTACT HAD BEEN MADE WITH US IN QUITE SOME TIME AND THAT WE MUST BE AT THE LIMITS OF DAYTON APCH'S AIRSPACE, I BROUGHT THIS UP TO THE CAPT WHO AGREED. I CONTACTED DAY APCH, WHO SAID WE SHOULD BE WITH ZOB. UPON CONTACTING CTR, THEY TOLD US THEY HAD BEEN ATTEMPTING TO CONTACT US FOR A LONG TIME. AGAIN, WE HEARD NOR REPLIED TO ANY ATC HDOFS. THE FLT ENDED UNEVENTFULLY, AND I DO NOT KNOW IF ANY ACFT WERE VECTORED AROUND US. I DO NOT FEEL THE ACFT'S RADIOS MALFUNCTIONED, AS THEY WORKED FINE DURING ALL KNOWN XMISSIONS AND RECEPTIONS, AND NO COMPLAINTS HAD BEEN MADE BY ANY PARTIES ABOUT OUR RADIOS. I BELIEVE IN BOTH INSTANCES, ATC FORGOT ABOUT US AND DID NOT HAND US OFF. ANOTHER MAJOR CONTRIBUTING FACTOR WAS FATIGUE. ALL 3 OF US WERE VERY TIRED AND HAD BEEN AWAKE FOR OVER 24 HRS STRAIGHT. THIS FATIGUE SLOWED OUR RECOGNITION THAT WE SHOULD BE TALKING WITH SOMEONE ELSE. ALTHOUGH WE WERE DEAD-TIRED, I DO NOT BELIEVE WE MISSED HDOFS IN EITHER INSTANCE. I HAVE CONSIDERED THE POSSIBILITY THAT WE ALL FELL ASLEEP DUE TO OVER-FATIGUE, BUT OUR AIRPLANE HAS NO AUTOPLT AND NEEDS FAIRLY CONSTANT ATTN TO ALT AND COURSE. WE WERE LEVEL AT OUR ASSIGNED ALT AND ON COURSE AT ALL TIMES. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR IS FLYING THE CASA 212. HE HAS NOT HEARD THAT THE ACFT HAS HAD ANY PROBS WITH ITS RADIOS. HE IS TRYING TO BE MORE AWARE OF THE ATC SIT BY ASKING FOR ALTIMETER SETTINGS 'EVERY 20 MINS OR SO.' THE FAA DID NOT CONTACT THE CREW REGARDING THIS INCIDENT. HE NOW UNDERSTANDS THAT PART 135 AIR FREIGHT TAXI OPS ARE REGULARLY VERY FATIGUING, AND FATIGUE IS STANDARD FOR THE INDUSTRY.

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.