Severe turbulence jolted a Tokyo-bound Northwest Airlines flight from the Philippines on Friday, injuring 50 passengers and crew members, a company spokesman said. Four passengers were hospitalized, including one person with a serious neck injury, said Masashi Takahashi, spokesman for Northwest Airlines in Tokyo. The 46 others, including seven crew members, received light injuries, he said. Turbulence hit the plane while it was circling off the coast of Chiba, east of Tokyo, about 30 minutes before landing at Tokyo's Narita airport, he said. The plane suddenly descended, sending passengers without their seatbelts fastened lurching from their seats, he said. The Boeing 747-400 plane was carrying 408 passengers and 14 crew members.