Flight Crew Air Transport Pilot (ATP)
Other / Unknown
Aircraft Equipment Problem Critical
Flight Crew Landed in Emergency Condition; General Declared Emergency; General Maintenance Action
Human Factors; Aircraft; Procedure
After two vectors off arrival; Center cleared us direct to a fix. At FL240; 270 KTS assigned; approximately 30 miles southeast of the fix; Center cleared us to descend via the arrival. I knew we were already very high on the profile and told First Officer that we needed to get down. First Officer went to level change and fully extended speedbrakes. This was not correcting our profile error of 3;000 FT high quickly enough and I told Center twice that we were going to have a problem making the 10;000 FT restriction. There was no response from Center on both occasions and I assumed that I was either stepped on or they were ignoring me. At approximately 15;000 FT; 270 KTS and approximately 2;000 FT high on profile I told First Officer that we needed to extend the slats in order to get down. First Officer started to reach to extend them and then realized that it was the pilot not flying's job and I extended them. Soon after we heard a loud bang and received a Slat Disagree warning; with no associated roll. I looked at the QRH and put the slats back up. The alert went away. We did make the 10;000 FT restriction. We extended the flaps early because I thought the problem might return and it did. We complied with the QRH; stowed slats; declared an emergency and made an uneventful landing; cleared runway; had emergency personnel look over the aircraft for damage and taxied to the ramp. Late descent by ATC and lack of ATC response led to perceived problems making altitude restrictions.
[During descent] on the RNAV arrival; we were vectored off; on; back off the arrival; then back on with a descend via clearance. We were high and getting higher to our 10;000 FT crossing restriction and we were slowed to 270 KTS or less. The tools we have are idle power; we were in level change starting at the first vector. Speed; we were slowed to 270 or less. Speedbrakes; they were full. The only additional tool is slats. To make the crossing restriction we selected slats at 270 KTS; 15;000 FT; 2;000 FT high on the vertical profile for crossing at 10;000. We got a SLAT DISAG after selecting slats followed by a hard plane shuddering thud on the right side of the aircraft. It is unclear if the 'boom' is associated with the slats or coincidental. We had queried ATC about the crossing restriction; and then with the slat disagree; we continued to try for the crossing restriction and made it; all while running the QRH and investigating the possible cause of the bang. The QRH was followed and a no slat/flap 28 landing at 190 KT was made by the Captain with uneventful results other than some very warm brakes. A SLAT DISAG is an abnormal we train for. The use of speedbrakes and slats to meet ATC constraints on a routine bases is unacceptable. The arrivals with vectors and speed restrictions followed by an unreasonable 'descend via' are no way to protect our aircraft serviceability in the long run.
MD11 flight crew reports a loud bang and a Slat Disagree warning while extending slats at 270 KTS during descent to make a crossing restriction. The Slat Disagree warning disappears when the slats are retracted; but reappears when extended during approach; resulting in a no slat flap 28 landing.