Narrative:

At dusk; inbound on ATC assigned right base leg vector (approximately 285 - 300 heading) for what appeared to be 5 NM final to runway 02. As is my technique - unless weather is a concern - I go into terrain mode descending thru approximately 16;000 feet MSL. Aircraft (AC) was descending on profile (gear down / flaps 30 / airspeed approximately 160kts). Relative to my pilot flying pfd; I was on a 10-NM terrain scale at this time.both visually and terrain mode-wise; I was aware of the smoke stack(s) / obstructions at the acs 11-o'clock position; roughly 6-7nm ahead as we descended. Terrain display showed height to be 1;900 feet MSL. Airport / runway 02 was in sight. We had a couple of towers off the right side of the AC; and we were 'visual relative to them' as I angled toward final (non-square pattern). At this time; we received a terrain GPWS warning. I added power; climbed approximately 200 feet. The GPWS warning ceased; and we continued on the base leg turn. Configured for flaps 45. Landing and all other procedures normal.not wanting to ever 'second guess' a warning system; it did its job. All I can think is that it was looking ahead to our projected ground path and descent rate as we angled to final for runway 02. Possibly; GPWS was looking at the towers off the acs right wing; but those towers were not on my terrain mode display (we did have them visually).as we talked about it after - and I reflect upon it now - we could have discussed the obstacles/threats even more as we vectored ourselves once calling the airport in sight. In hindsight; I would square my pattern off more; and thus hit that '5 mile final point' a little high; thus ensuring no potential GPWS warnings. In doing so; we would have ample distance/time to configure flaps 45 and land more straight-in.

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Original NASA ASRS Text

Title: An air carrier Captain experienced a GPWS terrain warning while on right base visual for Runway 2 at SGF. Climbing 200 feet silenced the warning which may have been caused by one of the radio towers in the area which were in sight.

Narrative: At dusk; inbound on ATC assigned Right base leg vector (approximately 285 - 300 heading) for what appeared to be 5 NM final to RWY 02. As is my technique - unless weather is a concern - I go into Terrain Mode descending thru approximately 16;000 feet MSL. Aircraft (AC) was descending on profile (Gear down / Flaps 30 / Airspeed approximately 160kts). Relative to my pilot flying PFD; I was on a 10-NM Terrain scale at this time.Both VISUALLY and Terrain mode-wise; I was aware of the smoke stack(s) / obstructions at the ACs 11-o'clock position; roughly 6-7NM ahead as we descended. Terrain Display showed height to be 1;900 feet MSL. Airport / RWY 02 was in sight. We had a couple of towers off the right side of the AC; and we were 'visual relative to them' as I angled toward final (non-square pattern). At this time; we received a Terrain GPWS Warning. I added power; climbed approximately 200 feet. The GPWS Warning ceased; and we continued on the base leg turn. Configured for flaps 45. Landing and all other procedures normal.Not wanting to ever 'second guess' a Warning system; it did its job. All I can think is that it was looking ahead to our projected ground path and descent rate as we angled to final for runway 02. Possibly; GPWS was looking at the towers off the ACs right wing; but those towers were NOT on my Terrain Mode Display (we did have them visually).As we talked about it after - and I reflect upon it now - we could have discussed the obstacles/threats even more as we vectored ourselves once calling the airport in sight. In hindsight; I would square my pattern off more; and thus hit that '5 mile final point' a little high; thus ensuring no potential GPWS Warnings. In doing so; we would have ample distance/time to configure flaps 45 and land more straight-in.

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.