Flight 7K9268 lurched up and down several times in the final moments before it lost contact with the ground, according to data from the Flight Radar 24 tracking site. The Airbus 321 climbed nearly 3,000 feet in three seconds before falling another 3,000 feet a few seconds later, the altitude data shows. It repeated the abrupt rise and fall a second time before it was lost to radar. The records from the Sweden-based Flight Radar 24 also show the aircraft rapidly losing speed in its last minute. This data is usually very reliable, but can sometimes be affected by an erroneous message. Alexander Smirnov, a top official at Metrojet, says its plane dropped 300 kph (186 mph) in speed and 1.5 kilometers (about 5,000 feet) in altitude one minute before it crashed into Egypt's Sinai Peninsula. The flight was at a cruising speed of just over 407 knots (468 miles per hour) at the beginning of the data set. Thirty seconds later the speed had fallen to just 62 knots (70 miles per hour) - far too slow for a plane that size to remain airborne. Dr Stephen Wright, who teaches aviation at the University of Leeds, pointed to the possibility of a "wayward act" which may have caused the sudden end of data transmission - and crash. "Looking at the numbers, it's confusing to me", he said. "If there was a catastrophic failure due to a wayward act that would cause significant damage and the aircraft could break up in flight." The sudden climb "would suggest it hit really terrible weather, an updraft, clear air turbulence. Those kinds of weather conditions are usually when you are flying over large expanses of water, and particularly tropical water. "I don't think that's possible in that location because it's over the desert." He added that the focus now is on "the information is in the black boxes - those are the items I am interested in now. "They will be listening to the cockpit recorder for unusual sounds. it records the voices and also the sounds at different locations, and you can triangulate where the sound came from and the type of sound."