EMB ERJ 145 ER/LR
Flight Crew Air Transport Pilot (ATP)
Human-Machine Interface; Other / Unknown
Aircraft Equipment Problem Less Severe; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Became Reoriented
Human Factors; Aircraft
Descending into AMA and given the GPS 22 approach cleared direct to a transition fix; cleared for the approach. Both FMS's looked good. Hit the fix and aircraft started turning the wrong way. As I was checking what might be the reason and about to ask for a heading; the Controller said I see you turning off course; what do you want to do? I said the FMS's still look good but aircraft turned the wrong way; give us whatever heading you need. We will reset the FMS's; request vectors to the approach. He gave us a couple of headings; asked if we were ready for the approach; I doubled checked everything; said yes. He cleared us for the approach and we flew the approach with no problem; landed. Thought about it a lot; First Officer and I talked about it. Still not sure why the aircraft did that as the courses looked good. The course lines were connected on both FMS's. We had already flown two other GPS's on this trip; one earlier that day with no problems. It shows the importance for the non-flying pilot's duty of monitoring the approach all the time in case of a glitch like this; rare as they are.
EMB-145 Captain experiences a turn in the wrong direction during a GPS Runway 22 approach at AMA; with the FMS and autopilot controlling the aircraft. Vectors are requested and the second approach is successful.