B717 captain reports slat disagree warning during approach although slats have extended normally. A ...

Attributes
ACN	816332
Time
Date	200812
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : zzz.airport
State Reference	US
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B717 (Formerly MD-95)
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 22000 flight time type : 5000
ASRS Report	816332
Events
Anomaly	aircraft equipment problem : less severe
Independent Detector	aircraft equipment other aircraft equipment : slat disagree warning other flight crewa
Resolutory Action	flight crew : overcame equipment problem
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

On arrival; as we extended slats; we got a slat disagreement alert. I had first officer recycle the slats. As they were extended again; the alert came back on. The autopilot was disconnected to see if there was any roll tendency indicating an asymmetric condition. The aircraft was in perfect trim. At this point we were sure we had an indicating problem; but to be sure we called up a check airman who was in the back of the aircraft. Captain went back and visually checked that the slats were extended. He then returned to the jumpseat. Gear and flaps extended normally. The only problem we had at this point was the aircraft did not recognize we had slats out and would not allow us to slow. I said I thought the best and safest course of action would be to turn off the afs switches and hand fly the approach. It was either that or fly a no-slat/no-flap approach which would be required if we had no slats extended or an asymmetric condition. Captain agreed. During the approach; the aircraft flew normally and completely in trim. After turning off the runway and retracting the flaps to 18 degrees; the slat disagreement alert went away. Aircraft had a slat disagreement alert. This can only be 1 of 2 things: an asymmetric condition; or a switch position disagreement (slat handle). Since we had no roll tendency; we concluded the aircraft thought it had no slats extended.

Original NASA ASRS Text

Title: B717 Captain reports slat disagree warning during approach although slats have extended normally. A normal full flap and slat landing ensues using manual thrust selection.

Narrative: On arrival; as we extended slats; we got a Slat Disagreement alert. I had First Officer recycle the slats. As they were extended again; the alert came back on. The autopilot was disconnected to see if there was any roll tendency indicating an asymmetric condition. The aircraft was in perfect trim. At this point we were sure we had an indicating problem; but to be sure we called up a Check Airman who was in the back of the aircraft. Captain went back and visually checked that the slats were extended. He then returned to the jumpseat. Gear and flaps extended normally. The only problem we had at this point was the aircraft did not recognize we had slats out and would not allow us to slow. I said I thought the best and safest course of action would be to turn off the AFS switches and hand fly the approach. It was either that or fly a No-Slat/No-Flap approach which would be required if we had no slats extended or an asymmetric condition. Captain agreed. During the approach; the aircraft flew normally and completely in trim. After turning off the runway and retracting the flaps to 18 degrees; the Slat Disagreement alert went away. Aircraft had a slat disagreement alert. This can only be 1 of 2 things: an asymmetric condition; or a switch position disagreement (slat handle). Since we had no roll tendency; we concluded the aircraft thought it had no slats extended.

Data retrieved from NASA's ASRS site as of May 2009 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.

B717 captain reports slat disagree warning during approach although slats have extended normally. A normal full flap and slat landing ensues using manual thrust selection.