Severe turbulence during a Honolulu-bound Northwest Airlines flight has injured eight passengers and a crew member.Northwest Airlines says Flight 22 from Tokyo landed on Thursday morning in Honolulu after encountering turbulence over Midway Island.Two passengers and a flight attendant were hospitalised with hip, head and neck injuries. The flight attendant was in serious but stable condition. The condition of the passengers was not immediately known.The flight carried 285 passengers.