One minute after MH370’s flight crew said “Good Night” to Malaysia air traffic controls, and five seconds after the plane passed waypoint IGARI at 1720:31 UTC, the plane’s Mode S signal disappeared from air traffic control screens. As it reached the border of the Ho Chi Minh Flight Information Region (FIR) approximately 50 seconds after that, the plane made an abrupt 180 degree turn. The radius of this turn was so small, and the ground speed so low, that it appears to have been effected via a semi-aerobatic maneuver called a “chandelle.” Similar to a “box canyon turn,” this involves climbing under power while also banking steeply. The maneuver offered WWI pilots a way to reverse their direction of flight quickly in a dogfight.
Chandelles are not a normal part of commercial 777 operation. They would not be used by pilots responding to in-flight fire.
The fact that such an aggressive maneuver was flown suggests that whoever was at the controls was highly motivated to change their direction of flight. Specifically, instead of going east, they wanted to go west.
At the completion of the left-hand U-turn the plane found itself back in Malaysia-controlled airspace close to the Thai border. It flew at high speed (likely having increased engine thrust and dived from the top of its chandelle climb) toward Kota Bharu and then along the zig-zaggy border between peninsular Malaysia and Thailand (briefly passing through the outer fringe of Thai airspace) before making a right-hand turn south of Penang. We know this “based mostly on the analysis of primary radar recordings from the civilian ATC radars at the Kuala Lumpur (KUL) Area Control Centre (ACC) and at Kota Bahru on the east coast of Malaysia; plus (apparently) the air defense radars operated by the RMAF south of Kota Bahru at Jerteh, and on Penang Island off the west coast,” according to AIN Online.
At 18:02, while over the small island of Pulau Perak, the plane disappeared from primary radar, presumable because it had exceeded the range of the radar at Penang, which at that point lay 83 nautical miles directly behind the plane. Then, at 18:22:12, another blip was recorded, 160 miles to the northwest.
The most-asked question about the 18:22 blip is: why did the plane disappear then? But a more pressing question is: why did it reappear? If the plane was already too faint to be discerned by Penang when it was at Pulau Perak, then how on earth could it have been detected when it was three times further away?
One possibility is that it was picked up not by Malaysian radar, but by the Thai radar installation at Phuket. An AFP report from March 2014 quoted Thailand’s Air Marshal Monthon Suchookorn as saying that Thai radar detected the plane “swinging north and disappearing over the Andaman Sea,” although “the signal was sporadic.”
At 18:22, the plane was approximately 150 miles from Phuket. This is well beyond the range at which Penang had ceased being able to detect the plane. What’s more, when the plane had passed VAMPI it had been only about 120 miles from Phuket. If it hadn’t seen the plane when it was at VAMPI, how was it able to detect it when it was 30 miles further? And why just for a momentary blip?
I don’t believe that, as some have suggested, the plane climbed, was detected, and then dived again. As Victor Iannello has earlier pointed out, the plane was flying at around 500 knots, which is very fast, and suggests a high level of motivation to be somewhere else, not bleeding off speed through needless altitude changes.
I propose that what happened at 18:22 was that the plane was turning. Entering into a right bank, the plane would turn its wings temporarily toward the Phuket radar station, temporarily presenting a larger cross section. Then, when the plane leveled its wings to straighten out, the cross section would shrink, potentially causing the plane to disappear. Continue reading How MH370 Got Away