EMB-175 flight crew reported temporary loss of control and excursion from assigned altitude due to severe turbulence.
Synopsis
EMB-175 flight crew reported temporary loss of control and excursion from assigned altitude due to severe turbulence.
Narrative
During the climb on the ZZZZZ SID; the crew monitored developing weather in the area and activated the radar to assess scattered clouds and light precipitation along our route. Aircraft X was cleared ZZZZZ DIRECT ZZZZZ1; and while ATC issued several weather-related advisories and deviations to other aircraft nearby; none were directed toward aircraft on our east-west route. Despite continuous scanning; no significant radar returns were detected. As a precaution; the Captain instructed the FAs to remain seated and advised passengers to buckle up.Approximately 30-40 miles from ZZZZZ1; the aircraft encountered unexpected turbulence that quickly intensified from light to moderate; with brief moments approaching severe. The aircraft experienced altitude variations of about ±200-300 ft and rapid VSI swings up to 3000 fpm. The Captain disconnected the autopilot to maintain tighter control. The most intense portion lasted around 30 seconds; with the full encounter lasting 2-3 minutes.After the turbulence eased; the aircraft was returned to FL340; and ATC was informed of the temporary 300-ft altitude deviation. The FA crew confirmed no injuries; and the remainder of the flight proceeded without further issues.
Second reporter narrative
Departed ZZZ on schedule. Pilot crew turned on weather radar shortly after takeoff due to scattered clouds and light precipitation on the SID departure ZZZZZ.Crew was given ATC routing ZZZZZ DIRECT ZZZZZ1. Approximately 30-40 miles from ZZZZZ1; ATC gave numerous weather advisories and deviation clearances to several aircraft in the vicinity; but none that were on a similar east to west routing as Aircraft X. Aircraft X did not get a specific advisory from ATC about weather or deviations. PF and PM continuously searched for precipitation radar returns to find the weather; but could not identify any. Out of caution; CA/PF gave direction to the FAs to remain seated (approximately XA30); then made an announcement to the passengers to return to their seats as we may encounter some rough air. At approximately XA40 we started to experience light; then moderate turbulence bordering on severe. Altitude deviations appeared to be +/- 2-300 ft with 2-3000 ft VSI indications. Due to the magnitude of the VSI swings and altitude deviations CA/PF disconnected the autopilot to prevent further altitude loss and override slow autopilot corrections. It appeared that we were in the turbulence approximately 2-3 min with the worst approximately 30 seconds. Once the moderate turbulence subsided we returned the plane to its assigned altitude of 34000 ft. We immediately notified ATC of the reason for the altitude deviation. ATC confirmed the altitude loss of 300 ft and noted the moderate turbulence. The captain called the FA crew to make sure everyone was okay. No injuries or problems noted. Crew continued to the destination without incident.Cause: Moderate bordering on severe turbulence.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.