At 6.24pm, there was suddenly a loud noise heard, which was actually caused by the pressure bulkhead's failure. This caused an explosive decompression. Air rushed out of the plane and blew off the tail of the plane. As all four hydraulic lines, which control the plane, are located in the tail, the plane became uncontrollable. 46 seconds later the pilots squawked 7700 (meaning that they are in an emergency) and requested to return to Tokyo International Airport. However, although the air traffic controller approved the plane to turn towards Tokyo, the plane strangely started heading towards the north-west direction. At 6.28pm, the Tokyo Air Traffic Controller asked the pilots to turn left, but received the message from the pilots, "now uncontrollable." By then, the plane was moving in a way called the phugoid motion, climbing until losing speed and stalling, then the nose goes down and gaining speed until the plane is able to climb again. The phugoid motion repeated itself until the end of the flight.