Date: 201810
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Weather elements / visibility: Windshear
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Landing
ATC / advisory: Tower ZZZ
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Ground Event / Encounter Object; Ground Event / Encounter Loss Of Aircraft Control; Ground Excursion Runway; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Regained Aircraft Control
Contributing factors: Human Factors; Procedure; Weather
Primary problem: Weather

Narrative: On approach; we experienced a 40-knot transition in airspeed just under 1;000 feet and I elected to go around. Approach speed was set for +20 knots per [procedure] and flaps 25. The entire low-level segment was turbulent. The Tower at that time was calling winds 310/30 gust 38 for the approach. Once we were configured for the downwind; I had the third pilot check the runway alignment at our alternate. The runway there had worse alignment for crosswinds than [our destination]. On downwind we had approximately 14.0 on fuel. We elected to attempt another approach as we did not think we had enough fuel to get out of this weather pattern. This approach; the winds were about the same but we did not encounter the plus 20 minus 20 airspeed change. I continued the approach and at approximately 200 feet; I had the Progress page 2 up and it showed a 27-knot crosswind. Before that; it had been between 27 and 32 knots. Landed the aircraft slightly left of centerline; speedbrakes were normal and all engines in reverse. Touchdown was fine; as we started approaching 90 to 100-knots the aircraft suddenly began veering to the right. Had full aileron in and left rudder maximum. Asked the First Officer to help with the ailerons and rudder while applying left brake. Felt like the nose gear just skidded; transitioned to tiller but did not seem to make any difference and we departed the runway. Just after touchdown; the Tower announced winds to another aircraft as 320/30 gust 45 and then said 'winds are all over the place'. We came to a stop in the grass between taxiways. The fire department had responded and we shut the airplane down while they approached and we were communicating with them on the radio. No injuries on aircraft. We elected not to emergency evacuate the aircraft. A scissor lift was brought out to the airplane for us to exit the aircraft. The wind was extremely strong; the operator was concerned that the lift may fall over. Once on the ground; the wind was variable and I would estimate well over 40 knots with higher gusts and appeared to be that strong the entire time we waited to exit. Maintenance did a preliminary exam of aircraft and nothing appeared to be damaged. We were told we took out one runway light. I believe we had experienced a high wind gust that pushed us nose right. [I] suggest not only cloud and ceiling be considered for suitable alternates but [also] high gusty winds. Need alternate out of the same weather pattern.


Second narrative: During final at 1;000 feet; I called the expected wind fluctuations of plus or minus 20 knots. I believe we were still coupled with the autopilot until about 200 feet; when [the Captain] finally disconnected. No wind shear alerts. About 500 feet; I asked for a wind check. Tower said the 'wind is all over the place.' It appeared the aircraft was stable as the wind had settled down; but I could still see [the Captain] wrestling the control inputs. We touched down normally; a little on the upwind side of centerline; but in control. I remember looking inside on touchdown to verify 'spoilers up - reversers normal.'As we began to decelerate; we started drifting (sliding) to the right and I noticed [the Captain] struggling to hold the ailerons. I instinctively reached up and helped him keep ailerons into the wind. We continued to drift right and I heard him say 'yeah; help me' or something like that; and I joined him on the rudder to find full left deflection and brake. About the time; I realized we were sliding off the runway (I could only guess at the airspeed).As we transitioned from pavement to grass; I suspected we took out a runway light; and started looking at gauges to see if we had any engine damage or other EICAS messages. They were all ok; stable at idle. I was trying to get a word in edgewise; but the Tower guy kept babbling on about something with an [air carrier] flight behind us. I finally said we were off the runway; in the grass; and if he could have the trucks come out.After the initial shock; composing ourselves; I remember staring at the gauges trying to decipher the information; everything looked normal. That's good. We started the APU; shut down engines and appraise the situation. About that time; [Maintenance] showed up and I contacted them on a discreet frequency; let them know we were in the process of shutting down and asked if they could verify our planes condition. I then contacted [company] and advised our location on the airport; aircraft condition and that we would need assistance. Took about 30 minutes to coordinate; and we deplaned via scissor truck. When being lowered from L1 door on the truck; we felt the full force of the gusty winds [and] it felt more than 40 knots. The fact that we derive alternates based on cloud conditions and visibility; not wind; is frustrating. On downwind after our first go around; we had many questions with little time to formulate answers. As a crew; we decided to give [destination] another try; though we would like to have had fuel for other options. [Our alternate] would not have been far enough to be out of the winds.


Synopsis: Air carrier flight crew reported a runway excursion occurred following loss of directional control while landing in a strong crosswind.