A Q400 flight crew called in fatigued following the first three legs of the third day of a poorly constructed flight sequence. The Captain questioned why the equally fatigued flight attendant crew was precluded from utilizing the same company provided checklist to determine physiological fitness for flight duties.

Narrative

My First Officer and I called in fatigued after approx 9 hours of duty on the third day of our trip. The trip started at 04XX on day one; 05XX on day two; and 10XX on day three scheduled out till 23XX on that day. Day two was incredibly challenging with holding; multiple approaches (missed approaches) early in the day; and horrific windshear on the last leg. I got to bed around 2300 on day two; but still woke up around 0430 on day three. I was unable to get back to sleep. On approach on our 3rd leg on day three; I was nodding off. My First Officer was doing crosswords to stay alert. We landed; taxied into the gate; deplaned; then shut the lights off and tried to nap for 30 minutes. It didn't work. We discussed the matter and decided to call in fatigued. There remains one factor that needs to be addressed. Our flight attendants were also fatigued; but were too afraid to refuse the assignment. As PIC I would not work with them. However; when I left the trip I was no longer PIC. But they continued to work the trip. Here is the problem as I see it. Flight attendants now hold certificates issued by the FAA. As certificated crewmembers; I feel that fatigue awareness guidelines also apply to them. They should not operate an aircraft while ill; stressed; drunk; or fatigued. And yet they are told they cannot call out fatigued because it is not a function of their contract. Yet it should be a function of law; and the company flaunts that. Is the FAA complicit with crew pushing? Does the FAA condone airlines pushing Flight Attendants to work fatigued and/or sick under penalty of termination? What am I to do as PIC when my flight attendants tell me they are unfit to fly? Do I push them toward termination by forcing them to call in; or should I operate the flight with an unfit crew? Please issue guidance on how we are to handle the situation. The event occurred due to shifting of the work schedule; going from early mornings to late night. Also; the duty periods on the first three days exceeded 10 hours (10; 12; 12). This trip was poorly constructed and based on the flawed premise that 'legal is safe'.