Narrative:

On arrival to seattle after the approach checklist was completed at 10;000 ft we were slowing to 210 KTS as assigned by ATC when we encountered severe wake turbulence from a preceding aircraft. The aircraft was rolled beyond 30 degrees of bank; with altitude deviation of around 200 ft and airspeed loss of around 20 KTS. The captain was pilot flying and immediately disengaged autopilot and went to maximum thrust while correcting the airplane's attitude. Control inputs were in my opinion not excessive but necessarily aggressive; and were as smooth as the conditions permitted. The entire event lasted probably about three seconds and we were back to straight and level; out of max thrust and recovering airspeed and altitude. I notified ATC and we were vectored away from the wake. We received a cabin call that our aft flight attendant was injured; advised ATC; got priority handling to the runway nearest our gate; coordinated to have medical personnel standing by at our gate; and made a normal; stable; but expeditious approach; landing; and taxi to park at the gate. Our forward flight attendant called us that she had helped [the injured flight attendant] and that [the injured flight attendant] said she was able to sit in her jumpseat and perform her duties during landing and parking. [The injured flight attendant] was immediately administered aid by medical personnel for having hit her head; shoulder; and hand; for abrasions; contusions; possible concussion; and lacerations suffered from hitting the aft door and the floor at her station. After the medical personnel reached her in the aft galley; passengers were allowed to deplane.

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Original NASA ASRS Text

Title: ERJ-170 First Officer reported 'severe' wake vortex encounter on approach to SEA that rolled the aircraft beyond 30 degrees of bank and resulted in injury to the Flight Attendant.

Narrative: On arrival to Seattle after the Approach Checklist was completed at 10;000 FT we were slowing to 210 KTS as assigned by ATC when we encountered severe wake turbulence from a preceding aircraft. The aircraft was rolled beyond 30 degrees of bank; with altitude deviation of around 200 FT and airspeed loss of around 20 KTS. The Captain was pilot flying and immediately disengaged autopilot and went to maximum thrust while correcting the airplane's attitude. Control inputs were in my opinion not excessive but necessarily aggressive; and were as smooth as the conditions permitted. The entire event lasted probably about three seconds and we were back to straight and level; out of max thrust and recovering airspeed and altitude. I notified ATC and we were vectored away from the wake. We received a cabin call that our Aft Flight Attendant was injured; advised ATC; got priority handling to the runway nearest our gate; coordinated to have medical personnel standing by at our gate; and made a normal; stable; but expeditious approach; landing; and taxi to park at the gate. Our Forward Flight Attendant called us that she had helped [the injured Flight Attendant] and that [the injured Flight Attendant] said she was able to sit in her jumpseat and perform her duties during landing and parking. [The injured Flight Attendant] was immediately administered aid by medical personnel for having hit her head; shoulder; and hand; for abrasions; contusions; possible concussion; and lacerations suffered from hitting the aft door and the floor at her station. After the medical personnel reached her in the aft galley; passengers were allowed to deplane.

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.