Date: 201812
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Aircraft: Widebody Transport
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Initial Approach
Airspace: Class B ZZZ
ATC / advisory: TRACON ZZZ
Aircraft component: Leading Edge Slat
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Human factors: Situational Awareness
Anomaly: Aircraft Equipment Problem Less Severe; Deviation - Speed All Types; Inflight Event / Encounter Weather / Turbulence; Inflight Event / Encounter Unstabilized Approach; Inflight Event / Encounter Fuel Issue
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Executed Go Around / Missed Approach
Contributing factors: Aircraft; Human Factors
Primary problem: Aircraft

Narrative: Just prior to top of descent for the ZZZZZ1 Arrival; ZZZ Center re-cleared us for the ZZZZZ2 Arrival due to ZZZ switching from Runway XX to XY. The latest ATIS was only about 15-20 minutes old and reported FEW clouds at 400 feet. I re-checked ATIS while the Captain loaded the new STAR and approach; and the new conditions were reported 3SM BR OVC003. Descent and arrival were totally normal. The Captain called for Slats Extend on downwind prior to being abeam the airport. We continued to configure during vectors on base and dogleg to final; reaching final landing configuration of 50/EXT with the Before Landing Checklist complete prior to passing 2000 MSL. We must have had the slats out for at least 3-4 minutes before intercepting the LOC and GS. At around 2000 MSL; we got unexpected stick shaker activation. I quickly looked around to confirm our configuration; airspeed; and thrust setting; and as I was looking at the Engine and Alert Display getting confident that we were safe; a Level 2 SLAT DISAG alert appeared. We were just getting slowed to our Vapp of 139 KIAS when this occurred. The Captain maintained airspeed and glideslope while we looked things over; but as soon as I stated that I thought we should go around; he agreed; added power; disconnected the autopilot; and commenced a very slow climb. I told Tower we were going around due to a slat problem. Airspeed at this time and throughout stayed above the lower amber airspeed foot by at least a few knots. As this go-around was due to questionable lift; neither of us was eager to clean up the wings quickly. We had initially leveled off more than we began to climb; and I started noticing a consistent speed of 143 knots with alternating amber and red airspeed numbers and a marginal climb rate of maybe a couple hundred FPM. When the Captain called for flaps 35; I told him we needed to add power and accelerate first. He stated that he was at max power; and after verifying that; I moved the flaps to 35. We began climbing a little more; and as we accelerated in the climb; the Captain properly called for incremental configuration changes of flaps 22; positive rate gear up; flaps 15; flaps up; and finally slats retract. The stick shaker stayed on for most of our initial clean-up; but I do not recall when it finally ceased. Only once the wings were clean did the Level 2 SLAT DISAG alert go away. The Captain had gone back and forth between autopilot and hand flying; so there was some confusion when I tried working the FCP (flight Control Panel) for him when the autopilot came off a second time. He seemed to want to fly and talk at this point but didn't state so until we were level or nearly level at 9000 MSL. At that point; he had the AP back on and took the radios and I got in the QRH. He told Approach Control we just needed vectors to go work our problem. Fuel was a concern for me as soon as we commenced the go-around; as the switch from Runway XX to XY ate into 3000 lbs of fuel according to the PROG page; with projected landing fuel going from 20;100 [pounds] to 17;000 [pounds]. However; we started climbing out with only 15000 pounds. Reaching 9000 feet we had 13600 [pounds]; and that was when I stated that I thought we should [advise ATC]. The Captain did so. As I was mentally weighing our options for landing location; knowing that the QRH would direct a no slat landing requiring a considerable runway length; the Captain stated at some point later during vectors that we could try one approach at ZZZ; then go to ZZZ1. I initially said ok; but later on I told him we wouldn't have the gas to make ZZZ1 and that we might be landing at [another alternate] if we went around again. He seemed to agree. Regardless; I was extremely glad the captain added 2000 pounds of fuel before I even met him at the folder. Original planned Fuel Over Destination for Runway XX was 15;800 [pounds]; and our flight plan #2 Fuel Over Destination was 17;800 [pounds]. We were clearly burning intoevery bit of that.Back to running the QRH. ..As I thought; the SLAT DISAG checklist directed a 22/RET landing since the alert didn't go away until the wings were clean. Surprisingly; the landing distance required for a dry runway was only 6600 feet conservatively. (Our gross weight was 326k pounds.) A wet runway would have required over 9000 feet; however. I double-checked ATIS and there were no Runway Condition Codes or precipitation reported; just mist; which we both figured was closer to dry for performance considerations. That was when the captain said we could try once at ZZZ; then go to ZZZ1. He also stated that we would use the overrun for stopping if necessary since we were a [priority]. I concurred. While on a downwind vector after things had slowed down; we heard an aircraft going around; presumably because they didn't break out. I queried the controller as to the type aircraft and approach used since the ILS Y and Z procedures have different minimums; but they didn't know. They did say that it was a [Large Transport] which didn't sit well with us since we figured they were using the lower minimums like us. However; Approach told us 2 more planes were in front of us and that we would know shortly if they had any issues getting in. They did not; so we continued. The two jets in front of us got in ok. As it turned out; at minimums all we saw were approach lights. The Captain continued (albeit without stating 'continue'). Prior to 100 feet AGL I clearly saw the green threshold lights and touchdown zone lights and confirmed 'landing' with the Captain; who was deeply focused on flying the jet at 190 knots to a safe landing. He did an excellent job of staying on the glideslope and not flaring too much given the extremely high airspeed and chance of floating excessively. He arrested the sink rate perfectly and landed well in the touchdown zone. We still used the overrun given to stop given our high airspeed. The brakes quickly heated up on taxi in; peaking at over 600 for many of them. We gave the ground crew a heads up that this was the case so that they could keep personnel clear. After blocking in airport authorities met us. We debriefed them and made the appropriate AML entries for the SLAT DISAG and hot brakes.I have had the same alert during the same phase of flight in the past. The first time we had plenty of fuel on board to enter holding and take our time running checklists and handling the [issue]. This time we had just enough gas to meet the company fuel policy. I can say that fuel helps mitigate the severity of this kind of situation. This time around; fuel quickly became as big of an issue as the actual problem with the aircraft; and it could have easily become the number one [problem] had our second approach not gone smoothly. FUEL MITIGATES ALL!




Synopsis: Wide body First Officer reported a leading edge slat issue led to hot brakes after landing.