Narrative:

Captain was PF (pilot flying); and I was pm (pilot monitoring). Last leg of the trip; we were at 27;000 ft.; indicated at the time of the encounter. Radar was up both sides; no indication of weather ahead as we were paralleling it off to our right. We had been at FL310; descended down to FL290; no improvement; then descended again to FL270. We had been there for approximately 15 minutes with continuous light-occasional moderate chop. Around kevv we experienced sudden erratic severe turbulence for the better part of 60-90 seconds. The airplane instantly went into an over speed condition for about 30-45 seconds; even with PF bringing the thrusters to idle immediately. I do not know how high the airspeed went; but we were in the red for about half of the time. As I was attempting to contact memphis approach with no avail due to radio congestion; we made the decision to start a descent without clearance. Once I was able to get through I told ATC about the turbulence we encountered; and they cleared us to descend. As we were descending; the turbulence was continuing so I asked for a left hand turn. Once we got to FL240; and a heading of around 020 we exited the conditions. There had been no reports ahead of such turbulence when I checked in prior to the encounter. I called up the flight attendants immediately to make sure that they were not injured and made sure the passengers were uninjured also. Then made a PA announcement to the passengers to reassure and ask the flight attendants to be seated for the remainder of the flight.

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Original NASA ASRS Text

Title: EMB 170 flight crew reported encountering unreported severe turbulence.

Narrative: Captain was PF (Pilot Flying); and I was PM (Pilot Monitoring). Last leg of the trip; we were at 27;000 ft.; indicated at the time of the encounter. Radar was up both sides; no indication of weather ahead as we were paralleling it off to our right. We had been at FL310; descended down to FL290; no improvement; then descended again to FL270. We had been there for approximately 15 minutes with continuous light-occasional moderate chop. Around KEVV we experienced sudden erratic severe turbulence for the better part of 60-90 seconds. The airplane instantly went into an over speed condition for about 30-45 seconds; even with PF bringing the thrusters to idle immediately. I do not know how high the airspeed went; but we were in the red for about half of the time. As I was attempting to contact Memphis Approach with no avail due to radio congestion; we made the decision to start a descent without clearance. Once I was able to get through I told ATC about the turbulence we encountered; and they cleared us to descend. As we were descending; the turbulence was continuing so I asked for a left hand turn. Once we got to FL240; and a heading of around 020 we exited the conditions. There had been no reports ahead of such turbulence when I checked in prior to the encounter. I called up the flight attendants immediately to make sure that they were not injured and made sure the passengers were uninjured also. Then made a PA announcement to the passengers to reassure and ask the flight attendants to be seated for the remainder of the flight.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.