AirAsia QZ8501: Why did the pilot of Flight QZ8501 request diversion?

Speculation is growing regarding changes to the route of missing Flight QZ8501. In particular, questions are arising to why lead pilot Captain Iriyanto requested a diversion from his planned flight path.

Weather conditions might provide an answer, possibly dense storm clouds, strong winds and lightning, officials said according to an AP report.

The Airbus 320-200 lost contact with the air traffic control tower in Jakarta early this morning, at 7.24am local time, according to Indonesian Transport Ministry official Hadi Mustofa. Exact details of the aircraft's final recorded manoeuvres remain unclear. Mr Mustofa said that the final communication from the pilot was a request to change height from 32,000 to 34,000 feet in the Kumai Strait near the island of Belitung, off the east coast of Sumatra, due to poor weather.

This conflicts with a statement by J.A. Barata, a Ministry of Transportation spokesman, who stated that the pilot asked to ascend to 38,000 feet to avoid clouds to the left of the aircraft. It was just five minutes later that the Jakarta tower lost contact with the plane. Mustofa also stated that the plane had asked for an unusual route before it lost contact.

Both pilots were experienced, discounting notions that human error lies behind the disappearance. According to AirAsia, lead pilot Captain Iriyanto (Indonesians frequently use only one name) had 6,100 flying hours experience and his first officer - believed to be French pilot Remi Emmanual Plesel - had 2,275 hours.

According to CNN television meteorologist Derek Van Dam bad weather gripped the area at the time of the disappearance. 'We still had lines of very heavy thunderstorms' he said. "But keep in mind, turbulence doesn't necessarily bring down airplanes."

However, according to reports in the Daily Mail, a leaked air traffic control sheet shows that the plane's speed had dropped to 353 knots, which suggests that it was having trouble climbing, possibly due to severe weather.

Whether weather was responsible for the plane's disappearance must remain moot for the time being. Aviation expert Geoffrey Thomas, in an interview with the Australian Channel Seven television network, stated that the fact that the pilots did not issue a distress call indicates that the plane might have undergone a sudden and catastrophic event. Such an event might not have been weather related.

Adding further weight to the notion that weather may not lie behind the disappearance is a posting by a Canadian A320 pilot on the aviation forum Aviation.net. He says that the weather conditions while the AirAsia flight headed north east were 'nasty' but that he did not believe they were sufficient to prompt major structural failure.