B757-200
Flight Crew Last 90 Days 60; Flight Crew Total 9700; Flight Crew Type 4200
Fatigue
Aircraft Equipment Problem Less Severe; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Overcame Equipment Problem
Aircraft; Human Factors
During climb out through FL250 we received a leading edge slat asymmetry EICAS message. We reduced speed and ran the leading edge asymmetry checklist. We leveled off and called Operations to update them on our status. We had time in flight so the Captain and I looked over the asymmetry checklist to make sure we did not miss anything and made a plan of action for our approach and landing. During the approach checklist we set the incorrect ref bugs. We went over the proper speeds during the leading-edge asymmetric checklist; but had it in our heads that we were landing flaps 20 so we set flaps ref 20 instead of ref 30 plus 30 as per the leading edge slat asymmetry checklist. During the approach we intercepted the localizer and glideslope over the outer marker. When the autopilot captured the glideslope we received a momentary stick shaker. The Captain disconnected the autopilot; reduce pitch and increased thrust to arrest the stick shaker. We continued the approach and landed uneventfully. After we got on the ground we question why we got the stick shaker and revisited the leading edge asymmetry checklist. That's when we learned of our mistake.  Looking back on our event I would have set the ref speeds after we finished the leading edge asymmetry checklist. Also fatigue played a role in the mistake.
A B757-200 First Officer reported the flight crew deviated from proper procedure while dealing with a leading edge slat asymmetry issue.