Seems the inquiry is nearly concluded
AVIATION / ONE-TWO-GO PHUKET AIR CRASH
Probe focuses on thunderclouds
AMORNRAT MAHITTHIROOK
A dense thundercloud capable of creating extreme turbulence is now suspected as a possible contributing factor in the crash of the One-Two-Go flight at Phuket airport last month, according to a source at the Transport Ministry. Initial findings had blamed wind shear with the associated sudden change in wind speed and direction for the disaster.
The source said a ministry panel investigating the accident had said that based on part of the information derived from the decoding of data from the flight and cockpit voice recorders, which are still undergoing analysis, the air crash that killed 90 people and injured 41, could have resulted from the plane flying through a tall, dense thundercloud.
The clouds can form alone, in clusters, or along a cold front in a squall line. Cumulonimbus (Cb) clouds form from cumulus clouds and can further develop into a supercell, a severe thunderstorm with special features.
He said investigators now believe the Cb could have played a major part in the Sept 16 crash.
A pilot of Orient Thai Airlines who had landed some four minutes before the ill-fated One-Two-Go flight informed the airport about the existence of a Cb cloud. Normally, a plane coming in later is supposed to circle for 10-15 minutes to wait for such a cloud to pass before making a landing.
The pilot in control of the OG269 flight might have seen the runway and decided to land, but the wind currents in the cloud could have thrown the aircraft off balance, the source said. The jetliner attempted the doomed landing in very heavy rain.
According to the source, Cb is the most dangerous cloud pilots have to contend with because it can hold rain, hail and thunderstorms and can cause a microburst. The collapsing air from the microburst can be strong enough to knock the plane off balance.
The investigative committee has learned from the Meteorological Department that sea wind changes off Phuket had caused a Cb cloud to develop around the moment of the air crash.
The wind shear factor is now not being taken too seriously because the plane had a wind shear detector that could warn the pilots of such a danger.
Chaisawat Kittipornpaiboon, transport permanent secretary who heads the probe panel, said wind shear was only one factor and his panel had yet to analyse many other suspicious factors before reaching a final conclusion on the crash.