EMB ERJ 170/175 ER/LR
Flight Crew Air Transport Pilot (ATP)
Situational Awareness; Other / Unknown; Fatigue
Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Air Traffic Control Issued New Clearance; Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Chart Or Publication; Human Factors; Weather
On departure from [Runway] 10L out of BOI airport; ATC asked us if we were flying runway heading or if we were tracking the 098 radial from BOI VOR. We then realized our mistake. We were in fact on runway heading and not tracking the 098 radial per the departure procedure. There was rising terrain to the north or left of our course and the wind was 30 KTS from the south; which was pushing us toward the terrain. We even had the terrain up on our MFD and I had made a comment about how something didn't seem right. At that point ATC gave us a right turn until we were higher than the terrain and then cleared us on course. We turned on course and at no time did we get an EGPWS warning.This was the last leg of the day for us and it was at night during IFR conditions. We had a scheduled 12 hour day; which I believe played a big part in this event. We were tired and I have personally noticed that after 10 hours of duty my attention to detail is reduced. I think it is unrealistic to maintain the same level of competency after 10 hours of duty. Neither one of us had ever been to BOI and were unfamiliar with the airport. We read over all the info available to us including the departure procedure but we misunderstood the chart. We thought it said runway heading and not track the radial. I think having this info on the company airport page as a reminder to all of us would be very helpful. There is info on the arrival part of the page but nothing for the departure.
When an ERJ-170 flight crew flew runway heading; 098 degrees; vice the BOI 098R per the SID; a strong south wind drifted them toward high terrain. An alert Air Traffic Controller questioned their track and then vectored them clear of the terrain.