Crj flight crew reported receiving a terrain warning on a dusk visual approach to lse.

Attributes
ACN	1563873
Time
Date	201807
Local Time Of Day	1201-1800
Place
Locale Reference	LSE.Airport
State Reference	WI
Environment
Flight Conditions	VMC
Light	Dusk
Aircraft 1
Make Model Name	Regional Jet CL65 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Final Approach
Flight Plan	IFR
Person 1
Function	First Officer Pilot Flying
Qualification	Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument
Person 2
Function	Pilot Not Flying Captain
Qualification	Flight Crew Instrument Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Deviation - Procedural Published Material / Policy Deviation - Speed All Types Inflight Event / Encounter CFTT / CFIT

Narrative:

Cleared visual with GPS FMS backup. Vectored in for visual; not on intercept course to GPS straight in. Captain had airport in sight; I did not but knew general area of field (referenced jeppesen graphic and noted field location in reference to major landmarks). As a crew we called field in sight. I began descent based on mental calculation; mistakenly assuming captain was visually backing up me with regards to runway alignment and visual descent point. Captain assumed I had a plan and situational awareness of runway. [Received] GPWS (ground proximity warning system) terrain message; captain momentarily took controls; momentary stick shaker. Corrected flight path and normal approach and landing.vertical guidance not set correctly. Communication breakdown. Failure to verify vertical guidance. Unfamiliar with airport at dusk. Never assume anything. Never assume in aviation. Never call field in sight unless pilot flying sees it.

Original NASA ASRS Text

Title: CRJ flight crew reported receiving a terrain warning on a dusk visual approach to LSE.

Narrative: Cleared visual with GPS FMS backup. Vectored in for visual; not on intercept course to GPS straight in. Captain had airport in sight; I did not but knew general area of field (referenced Jeppesen graphic and noted field location in reference to major landmarks). As a crew we called field in sight. I began descent based on mental calculation; mistakenly assuming Captain was visually backing up me with regards to runway alignment and visual descent point. Captain assumed I had a plan and situational awareness of runway. [Received] GPWS (Ground Proximity Warning System) terrain message; Captain momentarily took controls; momentary stick shaker. Corrected flight path and normal approach and landing.Vertical guidance not set correctly. Communication breakdown. Failure to verify vertical guidance. Unfamiliar with airport at dusk. Never assume anything. Never assume in aviation. Never call field in sight unless pilot flying sees it.

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.