Medium Transport; High Wing; 2 Turboprop Eng
Fatigue; Other / Unknown
Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance; Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented
Human Factors; Procedure
We got a reroute on the ground for radial to radial navigation to go to our destination. My First Officer (FO) and I pulled out an en-route chart and looked at it and then my FO entered it into the FMS and I was going to back that up with actually tuning the VOR and using the VOR's to navigate by. But neither of us expected to even have to do this as we just wanted direct DBL and normally you are able to get that.After we took off we actually had to fly what we were assigned.  We used the FMS to intercept the course and I brought up the VOR and then ATC asked us which radial we intercepted. Somehow even after looking it up and briefing it my FO managed to put it in the box and I managed to spin in the wrong the radial on my side to put us on the wrong radial. So we managed to navigate two separate ways wrong at the same time.Both the FO and I have been working a lot the past couple of months with lots of overtime and that is about the only thing that we could figure that would cause us to both mess up two different ways at the same time. For example this happened during XX of XY days on. I had worked X4 out of X6 on the day that it happened. My FO was in a similar situation.
Twin turboprop Captain reports receiving a clearance for Radial to Radial navigation to their destination. The First Officer sets up the FMC and the Captain attempts VOR raw data. Neither is successful. Fatigue was cited as a factor.