Narrative:

After takeoff and normal initial climb to 10000 ft we began an acceleration. At approximately 11000 ft, we got a master warning aural and master warning light. A message also appeared on EICAS (leading edge slat asymmetry) and a 'leading edge' warning illuminated. We activated the alternate leading edge switch once but got no change. Flaps and slats indicator showed full up. The aircraft was slowed to 240 KTS and the book abnormal procedure for that problem was accomplished. The warning light and EICAS message remained. After talking with company dispatcher and company maintenance coordinator, a decision was made to return to point of origin. I elected to not declare an emergency because we were offered a long clean dry runway (9000 ft). The procedure calls for an alternate (elect) extension of the flaps with the slats retracted and a threshold speed of vref (30) plus 30. I considered this to not be a problem on a 9000 ft dry runway. A normal (though a bit faster) approach was made followed by a normal touchdown and rollout. Reversers were used to 60 KTS and normal braking was applied. No other problem was encountered concerning the flight control problem, but, after landing, we realized we had not set the cabin to the new airport elevation. On this aircraft the pressurization is fully automatic, and the only thing required is to set the landing field elevation during preflight. A doublechk of this is on the descent checklist. We either missed setting it or misread the scale during the descent checklist. Therefore, after landing, the cabin had to adjust to departure field elevation. Maintenance later informed me that the slat problem was caused by a broken slat actuator.

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Original NASA ASRS Text

Title: CAPT OF ACR LGT ACFT RETURNED TO LAND AFTER HAVING A MALFUNCTION OF THE ACFT WING LEADING EDGE SLAT.

Narrative: AFTER TKOF AND NORMAL INITIAL CLB TO 10000 FT WE BEGAN AN ACCELERATION. AT APPROX 11000 FT, WE GOT A MASTER WARNING AURAL AND MASTER WARNING LIGHT. A MESSAGE ALSO APPEARED ON EICAS (LEADING EDGE SLAT ASYMMETRY) AND A 'LEADING EDGE' WARNING ILLUMINATED. WE ACTIVATED THE ALTERNATE LEADING EDGE SWITCH ONCE BUT GOT NO CHANGE. FLAPS AND SLATS INDICATOR SHOWED FULL UP. THE ACFT WAS SLOWED TO 240 KTS AND THE BOOK ABNORMAL PROC FOR THAT PROB WAS ACCOMPLISHED. THE WARNING LIGHT AND EICAS MESSAGE REMAINED. AFTER TALKING WITH COMPANY DISPATCHER AND COMPANY MAINT COORDINATOR, A DECISION WAS MADE TO RETURN TO POINT OF ORIGIN. I ELECTED TO NOT DECLARE AN EMER BECAUSE WE WERE OFFERED A LONG CLEAN DRY RWY (9000 FT). THE PROC CALLS FOR AN ALTERNATE (ELECT) EXTENSION OF THE FLAPS WITH THE SLATS RETRACTED AND A THRESHOLD SPD OF VREF (30) PLUS 30. I CONSIDERED THIS TO NOT BE A PROB ON A 9000 FT DRY RWY. A NORMAL (THOUGH A BIT FASTER) APCH WAS MADE FOLLOWED BY A NORMAL TOUCHDOWN AND ROLLOUT. REVERSERS WERE USED TO 60 KTS AND NORMAL BRAKING WAS APPLIED. NO OTHER PROB WAS ENCOUNTERED CONCERNING THE FLT CTL PROB, BUT, AFTER LNDG, WE REALIZED WE HAD NOT SET THE CABIN TO THE NEW ARPT ELEVATION. ON THIS ACFT THE PRESSURIZATION IS FULLY AUTO, AND THE ONLY THING REQUIRED IS TO SET THE LNDG FIELD ELEVATION DURING PREFLT. A DOUBLECHK OF THIS IS ON THE DSCNT CHKLIST. WE EITHER MISSED SETTING IT OR MISREAD THE SCALE DURING THE DSCNT CHKLIST. THEREFORE, AFTER LNDG, THE CABIN HAD TO ADJUST TO DEP FIELD ELEVATION. MAINT LATER INFORMED ME THAT THE SLAT PROB WAS CAUSED BY A BROKEN SLAT ACTUATOR.

Data retrieved from NASA's ASRS site as of July 2007 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.