Narrative:

[I felt a] sudden onset of excessive fatigue during flight due to fatigue-inducing pairing - not realized until about halfway through the flight. I felt fine on the first flight and had no indication of fatigue before starting the second leg. I was alert and well rested until halfway back to the domicile. Then I very quickly felt tired. I struggled to stay alert and focused. I drank coffee throughout the flights and got a good rest at the hotel prior to the flights. I found myself having to double check things more frequently and engaged in constant conversation to try to help. Going through customs and catching the hotel van had us up until far beyond normal waking time. I was fortunate that I made no mistakes - but there was much greater risk due to the fatigue.this and all others similar to it--created by crew planning and driven by marketing--are fatigue inducing pairings for the majority of pilots who fly them. Fundamentally; there are several characteristics these embedded all night pairings share in common: they operate outside of normal human waking hours; they include 'zone flipping' (where the pilot flies during normal waking hours in the first duty period and subsequently is required to fly starting when the previous duty day had ended--24 hours is not enough adaptation time; and; most critically; the pilot is required to turn and operate a second leg through normal sleeping hours and beyond his normal waking time (release beyond the pilot's local base time of normal waking by several hours accelerates the onset of fatigue.) I ponder how many of these situations go unreported and pilots fly fatigued due to the threat of not getting paid if they call in fatigued? The fatigue policy needs review. Note that these flights used to be layovers which released the pilot into rest in the very early morning hours. I had previously done that version and had no fatigue issues because we used to get to the hotel bed in a timely fashion. The pairings are now being built up to 10 hours of duty and over 6 or 7 hours of block time. That in itself is creating many fatigue issues. The failure to acknowledge and accept responsibility by the FAA and the airlines over the rampant; widespread fatigue in the skies is the direct cause of the unacceptable safety risks pilots; crew are passengers are subjected to daily. I hope that the promised upcoming rest rules are realistic and do not pander to the special interests.

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Original NASA ASRS Text

Title: An air carrier First Officer detailed the fatigue inducing effects of specific types of flight crew scheduled flight sequences.

Narrative: [I felt a] sudden onset of excessive fatigue during flight due to fatigue-inducing pairing - not realized until about halfway through the flight. I felt fine on the first flight and had no indication of fatigue before starting the second leg. I was alert and well rested until halfway back to the domicile. Then I very quickly felt tired. I struggled to stay alert and focused. I drank coffee throughout the flights and got a good rest at the hotel prior to the flights. I found myself having to double check things more frequently and engaged in constant conversation to try to help. Going through customs and catching the hotel van had us up until far beyond normal waking time. I was fortunate that I made no mistakes - but there was much greater risk due to the fatigue.This and all others similar to it--created by crew planning and driven by marketing--are fatigue inducing pairings for the majority of pilots who fly them. Fundamentally; there are several characteristics these embedded all night pairings share in common: They operate outside of normal human waking hours; They include 'Zone flipping' (where the pilot flies during normal waking hours in the first duty period and subsequently is required to fly starting when the previous duty day had ended--24 hours is not enough adaptation time; and; most critically; the pilot is required to turn and operate a second leg through normal sleeping hours and beyond his normal waking time (release beyond the pilot's local base time of normal waking by several hours accelerates the onset of fatigue.) I ponder how many of these situations go unreported and pilots fly fatigued due to the threat of not getting paid if they call in fatigued? The fatigue policy needs review. Note that these flights used to be layovers which released the pilot into rest in the very early morning hours. I had previously done that version and had no fatigue issues because we used to get to the hotel bed in a timely fashion. The pairings are now being built up to 10 hours of duty and over 6 or 7 hours of block time. That in itself is creating many fatigue issues. The failure to acknowledge and accept responsibility by the FAA and the airlines over the rampant; widespread fatigue in the skies IS THE DIRECT CAUSE OF THE UNACCEPTABLE SAFETY RISKS PILOTS; CREW are passengers are subjected to daily. I hope that the promised upcoming rest rules are realistic and do not pander to the special interests.

Data retrieved from NASA's ASRS site as of April 2012 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.