The last minutes: Jet turned right, then took a sharp left

CHENNAI: “Request weather deviation to the right.“ Those were the last words of the AN-32 pilot heard at the air traffic control at 8.46am before the plane disappeared from the radar at 9.15am.
“The aircraft took this right turn to avoid turbulence. Our records show the plane's last manoeuvre, however, was a sharp left turn with rapid loss of height from its flying altitude of 23,000ft.There was no mayday call,“ said an ATC source.
The aircraft was to land at Port Blair at 11.30 am and had fuel for four hours and 15 minutes of flying. The pilot had earlier called the ATC to report the plane's position on high frequency voice communication and did not report anything unsual. It never communicated of having reached the next point.
There are two such points on Chennai-Port Blair route where defence pilots use radio to inform about flight altitude, speed and course beyond radar coverage area from Chennai airport and Tambaram airforce base. This is strictly followed because air force and coast guard planes do not have modern surveillance sensors like commercial aircrafts.
“The pilot reported weather disturbance and asked for a right turn to deviate towards south and fly around the turbulence. But the disturbance was not reported in the weather chart and the pilots were regulars on the Sulur-Tambaram-Port Blair route,“ a source said.
Experts at IAF hint at at three reasons for a probable crash: A mechanical failure; fuel leakage, or a fire that disabled controls. The last one is talked about since the pilot appears not to have got time to make a mayday call. None of the planes flying at a higher altitude picked up a distress call. The 25-year-old plane is a transport carrier and is not equipped with modern surveillance machines used to track planes where radar coverage is weak. It may not have efficient sensors to detect mechanical failure, an expert said.
“AN-32 usually flies at around 21,000ft which is much lower than that of commercial carriers. Blips usually go off the screens for planes that fly at such low altitude once they cross 150 nautical miles from Chennai,“ said an official.