McDonnell Douglas Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Situational Awareness; Confusion
Aircraft Equipment Problem Less Severe; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Fuel Issue
Flight Crew Executed Go Around / Missed Approach; Flight Crew Landed in Emergency Condition; General Declared Emergency; General Maintenance Action
Aircraft; Human Factors
We arrived with flight plan fuel of 17;000 pounds. During the ILS approach we weighed 325;000 pounds; we selected flaps 35; Vapproach speed was 140 knots. When we slowed through 150 knots; we got stick shaker and SLAS DISAG alert. We did a go around and asked for another approach. We added speed for the second ILS approach. The new speed was 145 knots. During this approach; we got the same alert and stick shaker at the same place; 150 knots. We did a go around again. Next we executed the SLATS DISAG checklist. This prompted us to land flaps 22 with slats retracted. I; the captain now became the pilot flying. During our third approach we [advised ATC] because our fuel load was less than 11;000 pounds. For this approach the V approach speed was 188 knots. We touched down in the touchdown zone and applied light to moderate braking. During taxi in to the ramp; we received one brake overheat alert at 590. This SLAT DISAG problem became a repeat write up.
On approach I was pilot flying; about 3 miles on final slowing to approach speed (140) gear down and flaps 35; the airspeed foot rose significantly for no reason (we were stable) and we got the stick shaker/stall warning. This happened around 145 KIAS. Accomplished a visual missed approach; coordinated with tower; and talked to approach for vectors for another approach. Flew same approach with about 10 KIAS more added to final approach speed; but got same indication; stick shaker/stall warning approaching about 155 KIAS so accomplished a second missed approach. Asked for an extended downwind and Captain ran the SLAT DISAGREE checklist; after which he took the airplane after we turned on extended final and flew a 188 KIAS Flap 22/no slat approach; Captain landing. The approach and landing were uneventful; we monitored the brakes for any overheat; the highest temp we saw was 565 with carbon brakes after we taxied to parking normally. The brakes began to cool after that. The logbook contained a previous write-up of a similar problem with the stick shaker some days prior. Maintenance debriefed fully. Some problem either in the slat sensor or airspeed sensor. There was some erratic movement of the lower airspeed foot that I observed when pilot not flying. Make good determination of your problem and accomplish appropriate checklist. I believe that is what we did.
A Mcdonnell Douglas widebody flight crew experienced a stick shaker and SLAS DISAG alert as the aircraft was slowed through 150 KTS during approach. A go-around is initiated and a second approach with higher Vspeeds results in the same alerts and another go-around. The next approach is accomplished with the slats retracted to a successful landing.