Air carrier flight crew received obstacle alert for towers during approach and climbed to avoid them...

Narrative:

On arrival to okc 17L; cleared the 'visual approach outside of golfs waypoint on the ILS; captain choose your go direct to hangs'. We were offset to the east approximately 7 NM. Outside of golfs; altitude is 4;000 ft; inside to hangs is 3;000 ft; so captain dialed in 3;000 ft as we were inside of golfs; but we were still offset of the final course. We got an obstacle alert at approximately 3;300 ft; approximately 1-2 NM northeast of a tower group depicted on the approach plate. Approach control called out the towers as the captain initiated a climb of a couple hundred feet to increase the tower crossing clearance altitude. We could have coordinated and reviewed the approach plate and plan better prior to executing the cutoff of course to final. The towers in question were the highest obstacles on the approach. Additionally; the towers were very difficult to see at night because the lights blended into the city surrounding lights and at times appeared to be straight; lighted roads. A little better briefing and review would have prevented the alert. Aircraft systems worked flawlessly however; as well as ATC involvement helped to gain altitude to increase the altitude crossing safety margin. Fly the instrument approach plate as depicted to avoid any threats is a good idea.

Original NASA ASRS Text

Title: Air carrier flight crew received Obstacle Alert for towers during approach and climbed to avoid them.

Narrative: On arrival to OKC 17L; cleared the 'visual approach outside of GOLFS waypoint on the ILS; Captain choose your go direct to HANGS'. We were offset to the east approximately 7 NM. Outside of GOLFS; altitude is 4;000 ft; inside to HANGS is 3;000 ft; so Captain dialed in 3;000 ft as we were inside of GOLFS; but we were still offset of the final course. We got an Obstacle Alert at approximately 3;300 ft; approximately 1-2 NM northeast of a tower group depicted on the approach plate. Approach Control called out the towers as the Captain initiated a climb of a couple hundred feet to increase the tower crossing clearance altitude. We could have coordinated and reviewed the approach plate and plan better prior to executing the cutoff of course to final. The towers in question were the highest obstacles on the approach. Additionally; the towers were very difficult to see at night because the lights blended into the city surrounding lights and at times appeared to be straight; lighted roads. A little better briefing and review would have prevented the alert. Aircraft systems worked flawlessly however; as well as ATC involvement helped to gain altitude to increase the altitude crossing safety margin. Fly the instrument approach plate as depicted to avoid any threats is a good idea.

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.

Attributes
ACN	1758012
Time
Date	202008
Local Time Of Day	1801-2400
Place
Locale Reference	OKC.Airport
State Reference	OK
Environment
Light	Night
Aircraft 1
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach
Route In Use	Visual Approach
Flight Plan	IFR
Person 1
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 41
Events
Anomaly	ATC Issue All Types Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Inflight Event / Encounter CFTT / CFIT