MD-11
Flight Crew Air Transport Pilot (ATP)
Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Weather / Turbulence
Flight Crew Regained Aircraft Control
Weather
At approximately 100 miles West of ZZZZZ at FL310 ZZZZ Radio descended us to FL300 due to traffic.  At approximately 50 miles West of ZZZZZ we encountered extreme wind shear with gains/losses of 25-30kts and gains/losses of 500 feet in altitude. The winds were about 270/125. The autopilot disconnected twice with multiple stick shaker activations; (3 or 4 times); accompanied with tail-wind shear alert displayed on Captains PFD (Primary Flight Display).  At one point the airspeed was 5kts about the foot with MAX Power selected and we were still unable to maintain altitude.  I advised that we were unable to maintain our altitude and that we were descending and requested a block altitude of FL270-280. This was approved by ZZZZ Radio. The aircraft was under control and able to maintain altitude at FL280 with the spot winds  of 270/65 in continuous moderate turbulence.  This lasted for about another 5-10 minutes.  We remained at FL280 until climbing at ZZZZZ1 to FL310 and talking to ZZZ Radio.  The First Officer did a very good job of controlling the 'attitude' of the aircraft throughout the entire event.
ZZZZ [ARTCC] descended us from FL310 to FL300 due to traffic approaching ZZZZZ. We were already experiencing light turbulence and had slowed to 0.81 Mach. Pretty quickly after leveling off the turbulence escalated to a severe level. Autopilot (AP) maintained altitude about +/-200 ft and I was overriding the throttles to stay out of either foot. We were +/-15 knots and +/-20 deg bank. A few seconds later the AP disconnected itself and the aircraft started rolling due to the turbulence. I recovered to level flight on altitude and reset the AP. Almost right away the turbulence escalated further to extreme. The A/C (Aircraft) was yawing; rolling +/-30 deg altitude +/- 500 ft and airspeed was +/- 25-30 KIAS. At this point the AP fell offline again and I took over hand flying focusing on airspeed and attitude. There were many positive and low or negative G excursions. During this time there were multiple stickshaker activations and a TAIL WINDSHEAR indication. We were using HF (High Frequency) to communicate with ZZZZ (poor reception) and CPDLC (Controller Pilot Datalink Communications) was not working. The Capt advised ZZZZ of the turbulence and asked for a descent and a block altitude and was told to 'stand by'. With MAX power selected the aircraft would not accelerate until we descended. He advised them we were descending as we could not maintain altitude. Eventually ZZZZ cleared us a block altitude FL270-280 after we had descended to FL280 on our own. The rough air continued for another 5 minutes at a reduced level (light-moderate) and smoothing out. The winds at altitude were 270/125 when the event began and when it was over had decreased to 270/65. We did not enter either foot during the event. AP reconnected level at FL280.
MD11 flight crew encountered extreme turbulence in cruise.