B757 Undifferentiated or Other Model
Flight Crew Last 90 Days 193; Flight Crew Total 7430; Flight Crew Type 384
Flight Deck / Cabin / Aircraft Event Illness / Injury; Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Wake Vortex Encounter
Flight Crew Regained Aircraft Control; General Physical Injury / Incapacitation
Environment - Non Weather Related; Procedure
The incident occurred at 300 KIAS on the HYPER5 arrival approximately 15 Miles north of TUKRR at approximately 30;500 feet while descending to FL280.  We were in clear VMC conditions; with no forecast or potentially obvious indications of upcoming turbulence.  The seat belt sign was off.  At the time of the event; the aircraft experienced an uncommanded large vertical up and down motion and simultaneous right bank of approximately 30 degrees.  I was the pilot flying and the autopilot was on at the time of the event.  I immediately disengaged the autopilot and returned the aircraft to a safe state and back on the intended path.  The Captain immediately turned on the seat belt sign; reported the event to ATC; and contacted the cabin crew to assess injuries.  The ATC controller upon hearing of the event reported that there were no previous reported incidents in the area; and suggested that the event may have been a wake turbulence encounter from the preceding A380 (super category aircraft; approximately 10 miles in front of us on the same arrival).  Based on the characteristics of the encounter we agreed with that assessment.Initial reports from the cabin crew indicated that all crew and passengers were unharmed; however subsequent reports after further query by the Captain indicated that one of the flight attendants had hit her head and sustained a wrist injury.  In addition; during passenger deplaning; we were informed that a passenger had sustained a knee injury.  Once informed of the injuries; the Captain informed dispatch and ATC and requested that emergency medical services (EMS) meet the aircraft at the gate.  Declaring an emergency was discussed by the Captain and I; but deemed unnecessary given the nature of the injuries and because ATC was already giving us an appropriate degree of traffic priority; and EMS meeting us at the gate had already been coordinated through dispatch and ATC.  The subsequent approach and landing were uneventful.  We taxied to the gate and EMS met the aircraft.  Post flight procedures were normal and uneventful and we informed operations and the [flight operations manager]; as well as following up with queries from Potomac Approach and Station Maintenance.
[Report narrative contained no additional information.]
B757 flight crew reported 'severe' wake turbulence in trail of an A380 on the HYPER5 Arrival to IAD.