B767 flight crew reported extreme storm conditions during the final approach resulting in loss of control. The flight crew managed significant airspeed and altitude deviations which resulted in a go around.
Synopsis
B767 flight crew reported extreme storm conditions during the final approach resulting in loss of control. The flight crew managed significant airspeed and altitude deviations which resulted in a go around.
Narrative
On arrival into ZZZ we encountered severe turbulence on base for Runway XXR. We were paralleling a line of heavy precipitation running on a line from northeast to southwest. The Controller asked if we could accept the visual approach just as we entered the clouds; so the visual was not an option. We were in a vertical speed descent around 700 FPM. Shortly after entering the clouds; we were given a turn and the speed very quickly went from approximately 210 kts. to 280 kts. over speeding the flaps. The speed brakes were immediately extended and thrust levers to idle to help control the over speed situation. The over speed lasted for a few seconds then quickly reversed to the point where the stick shaker was activated. The autopilot was disconnected to recover from the shaker. The bank angle warning also activated once during the recovery. The speed was going up and down quickly and the shaker activated three times. We were quite task saturated at this time. The speed brake was inadvertently left fully extended. We were on intercept heading to the localizer and maintained an easterly heading and climbed during the recovery. This led to a conflict with the traffic on approach to XXL. The turbulence and speed fluctuations were quite extreme. The Controller asked us if we were climbing and I responded we got into weather. After we cleared the turbulence area we engaged the autopilot and the Controller vectored us to the west at 3000 ft. Several other flights aborted their approaches shortly after our event.This was some of the most extreme speed fluctuations I have ever seen. I always try to avoid convective areas. The radar showed us paralleling a line of moderate rain. This whole event occurred southeast of any precipitation. The cloud we entered didn't have any precipitation or have a convective appearance to it. There was no lightning and the ride was fairly smooth until the airspeed climbed rapidly. In retrospect I would have given a wider margin to this weather system. The winds at 3000 ft. were around 60 kts. We were in contact with our Dispatcher inbound to the airport and thought the worst weather was West of our position. I would have also communicated our situation to the Approach Controller in a more timely manner.
Second reporter narrative
The incident happened on base for Runway XXR when we were vectored into a storm cell about on a 7 mile final. Initially we were VFR on down wind to XXR expecting to turn short of the weather on a visual approach. ATC was busy with the weather and other arriving aircraft and turned us a little later than we were expecting to base and we went into the clouds. There was no turbulence prior to entering the clouds; and we stayed away from the red line of storms on the radar. I did not expect as rough of a ride as we received because the air was smooth prior to penetration and we were in front line of storms. As we entered the clouds we were at about 3300 ft. descending to 3000 at 210 kts. IAS; flaps 1. In an instant we started to accelerate past 250 knots while hitting severe turbulence. I pulled the throttles to idle and deployed the speed brake fully while holding the throttles to idle and we continued to accelerate to 280 kts. and started to pitch over to maintain altitude. We asked for and immediately were given a turn towards final. We were on a heading to join the localizer away from the weather when the stick shaker activated. It happened 3 short times very quickly. We disengaged the autopilot and applied the throttles to max. I felt the Captain's hand push on the base of the throttles to ensure we were at max power. We received a bank angle warning shortly after disengaging the auto pilot because we were still in a bank on the turn to final approach course. At this point we rolled wings level but started a climb because of the additional power and severe turbulence we were in. The stick shaker started at 195 IAS; flaps 1 with speed brakes extended. We experienced increasing and decreasing performance quite quickly. While trying to maintain aircraft control and our altitude; I went from full yoke forward to a level yoke on the overspeed; and idle thrust to max thrust a couple of time trying to maintain aircraft control and not over speed the flaps again. The turbulence was so severe it was difficult to see the instruments; while making communication inside and outside the aircraft difficult. This was the most severe turbulence I have ever experienced. Due to the severe conditions we were in; the aircraft climbed to an altitude of around 4100 ft. during the recovery on a heading away from the weather towards the localizer. ATC queried us about the altitude gain and we should have told them about the severe weather we encountered; but we failed as we were trying to get the aircraft under control and back to 3000 ft. Once out of the weather we reengaged the autopilot started a descent back to 3000 and received vectors from ATC to land on Runway YYL. The two aircraft behind us experienced similar conditions; so a runway change was initiated. The Captain wrote up the overspeed. There was no overspeed annunciation; or wind shear annunciation on tail XXX. Mitigation. Have a better plan. Don't fly into the thunderstorm. The short visual approach is fine unless you have to extend for any reason. Maintain required distance from storms; communicate as soon as possible so ATC is informed and can make good decisions pertaining to other traffic. Recognize and initiate wind shear recovery procedures at an earlier point and notify ATC as soon as possible when deviating.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.