AirAsia flight QZ8501: Aviation expert says plane should have flown around bad weather, not above it

An official from Indonesia's national search and rescue agency in Medan, North Sumatra points at his computer screen to the position where AirAsia flight QZ8501 went missing on Dec 28, 2014. An American aviation expert has said that it is "standard p
An official from Indonesia's national search and rescue agency in Medan, North Sumatra points at his computer screen to the position where AirAsia flight QZ8501 went missing on Dec 28, 2014. An American aviation expert has said that it is "standard practice" for commercial planes to fly around bad weather instead of above it, as it seems to have been in the case of AirAsia flight QZ8501. -- PHOTO: AFP

SINGAPORE - It is "standard practice" for commercial planes to fly around bad weather instead of above it, as it seems to have been in the case of AirAsia flight QZ8501, an aviation expert has said.

Should the plane enter a cumulunimbus cloud, a dense towering cloud associated with thunderstorms, several problems may arise, said Mark D Martin of United States-based firm Martin Consulting. These include heavy updrafts and downdrafts, and a dramatic loss in altitude, he said.

Air Asia Indonesia said the pilot of a flight that went missing between Indonesia and Singapore early Sunday had requested "deviation" from its flight plan because of bad weather. It had been flying at 32,000 feet and had asked to fly at 38,000 feet to avoid clouds.

If the plane had flown into a thunderstorm when it was between 31,000 ft to 38,000 ft in the air, icing on control surfaces while in the cloud can also freeze corrective pilot actions, and provoke aggressive aircraft manouevres, said Mr Martin.

"As pilots flying in those regions are specifically checked out to fly in regional airspace conditions with an instructor, which is heavy clouds, weather, traffic and winds, despite having the best weather radar installed on the aircraft, standard practice is to fly around weather rather than above it," he said.

He added that with 155 passengers on board, it appears that the aircraft was "heavy" and the fuel in its tanks "was not entirely burnt" to allow the plane to climb.

With a sea mass that spans nearly 2,000 islands, Indonesia maintains and operates one the region's "most formidable" search and rescue operations backed by a well-structured Coast Guard, Maritime Surveillance and modern coastal petrol and rescue aircraft and helicopter fleet, Mr Martin said.

"In the unfortunate event of AirAsia Flight QZ 8501 ditching into the sea, it does become clear that at least one of the three Emergency Locator Transmitters broadcasting on the universal Emergency Frequency of 121.5 Mhz should have activated," he said.

jalmsab@sph.com.sg