Narrative:

We were established on the RNAV (GPS) runway 1 at rut. We flew the published step downs as depicted. Upon reaching wirax which is the FAF; at a mandatory altitude at or above 3;800' msl; we continued the decent as published to 3;100' msl which is the altitude MDA on the approach. Leaving 3;800' and somewhere between there and 3;600' we received a taws warning for terrain; and it repeated; 'caution terrain too low; terrain terrain pull up.' keep in mind we both had our taws overlaid on our pfd's and didn't see any threat according to the picture. Without hesitation; I elected the go around; selected the to/GA button disconnected the autopilot and flew vx at full power away from the 'threat' and preceded to fly the published missed approach. We contacted ATC and advised we would like the RNAV (GPS) Z 19 at rut. In addition the winds now favored the RNAV 19. After the flight we evaluated; and we couldn't figure out why the taws gave us a terrain message; we were flying the approach as published.

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Original NASA ASRS Text

Title: A PC-12 flight crew flying the RNAV (GPS) Runway 1 IAP at RUT received a TAWS alert shortly after beginning their descent from the FAF; WIRAX; to the MDA of 3;100 MSL. They executed a go-around and requested and safely completed the Runway 19 RNAV approach.

Narrative: We were established on the RNAV (GPS) runway 1 at RUT. We flew the published step downs as depicted. Upon reaching WIRAX which is the FAF; at a mandatory altitude at or above 3;800' msl; we continued the decent as published to 3;100' msl which is the altitude MDA on the approach. Leaving 3;800' and somewhere between there and 3;600' we received a TAWS warning for terrain; and it repeated; 'caution terrain too low; terrain terrain pull up.' Keep in mind we both had our TAWS overlaid on our PFD's and didn't see any threat according to the picture. Without hesitation; I elected the go around; selected the TO/GA button disconnected the autopilot and flew VX at full power away from the 'threat' and preceded to fly the published missed approach. We contacted ATC and advised we would like the RNAV (GPS) Z 19 at RUT. In addition the winds now favored the RNAV 19. After the flight we evaluated; and we couldn't figure out why the TAWS gave us a terrain message; we were flying the approach as published.

Data retrieved from NASA's ASRS site 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.