Teams recovered four more bodies as rough weather continued to hamper the hunt for recorders from the crashed AirAsia Bhd. (AIRA) jetliner that could show whether icing contributed to the accident.
The AirAsia plane that disappeared Dec. 28 appears to have flown into a storm cloud, with the jet’s engines possibly affected by ice formation, researchers from the Indonesia weather office wrote in a report, citing meteorological data from the flight’s last known location over the Java Sea.
The jet flew through cloud clusters “similar to several previous incidents caused by weather conditions,” according to a translation of the Indonesian-language report. Infrared data from a weather satellite showed that temperatures in the clusters Flight 8501 went through were as low as minus 85 degrees Celsius (minus 121 degrees Fahrenheit), “meaning there were droplets of ice inside the clouds,” the report said.
While indications that the plane flew through icing conditions may help investigators form theories, only the data and cockpit-voice recorders can reveal the specific role ice played in events leading to the crash. Investigators will also have to examine the availability of up-to-date weather reports to the cockpit, pilot behavior and the role of infrastructure including air-traffic control.
Divers, helicopters, planes and ships are scouring the Java Sea for the Airbus Group NV (AIR) A320-200, which went down with 162 people on board.
“The weather is very, very wet sometimes,” Bambang Sulistyo, head of Indonesia’s search and rescue agency, told Bloomberg TV in an interview today. “So we face a little bit of a handicap to find it. Many neighboring countries have also helped with the system to find the black box.” The presence of mud is also hampering efforts, he said.
The Indonesian navy has found bodies still strapped in their seats and debris resembling parts of the tail, Colonel Yayan Sofyan said in an interview on Metro TV. The tail is the location for the flight-data and cockpit-voice recorders.
Members of an Indonesian search and rescue team carry the body of a passenger from the missing AirAsia flight 8501, after being delivered by a Singapore Super Puma helicopter from the Republic of Singapore Air Force RSS Persistence in Pangkalan Bun on Jan. 4, 2015.
Indonesia has five vessels equipped with hydrophones to try and pinpoint the recorders, which are designed to emit a “pinging” for at least 30 days after a plane crashes in water. An additional vessel equipped with listening equipment will arrive from China tomorrow, investigators said.
Recovery efforts are focused near Pangkalan Bun, about 600 miles (1,000 kilometers) southeast of Singapore. The international team set 1,575 square nautical miles (5,400 square kilometers) as the most likely area to find the wreckage, Malaysian Navy Chief Abdul Aziz Jaafar said in a Twitter post.
Indonesia said previously that AirAsia wasn’t authorized to fly to Singapore the day its jet crashed and halted the route pending an investigation. After the crash, the country is probing all airlines for any route violations.
Officials involved from state air-navigation operator AirNav Indonesia and state airport operator PT Angkasa Pura 1 are temporarily not allowed to work in operations, Djoko Murjatmodjo, director-general for air aviation transport at transport ministry, said in a press conference in Jakarta today.
More than 90 vessels and aircraft have been involved in the search operation, which has so far found objects including what appears to be an emergency door and an evacuation slide.
The fact that some of the bodies were recovered wearing seat belts suggests the plane may have suffered an aerodynamic stall rather than an in-flight breakup at high altitudes, said Robert Mann, head of aviation consultant R.W. Mann & Co. in Port Washington, New York.
Flying at 32,000 feet, the pilot asked to move to a higher altitude, citing clouds, officials have said.
An “abnormal situation occurred” at that height, said AirNav Indonesia, the nation’s air-navigation operator. Air traffic control gave the plane permission to ascend to 34,000 feet after checking flights in the area and coordinating with other airports, according to Bambang Tjahjono, AirNav’s head.
Ice formation has been a factor in several accidents in the past decade.
In the crash of Air France Flight 447 in 2009 in the Atlantic Ocean off Brazil, airspeed sensors on the Airbus A330 showed pilots a sharp drop in speed readings after the plane entered ice clouds. The lack of proper speed readings turned off the autopilot, forcing pilots to fly the jet manually.
The pilot in control, the least experienced of three on board, appeared to have panicked as the plane went into an aerodynamic stall, sending it into a climb that prevented it from gaining speed. The cockpit-voice recorder gave no indication whether pilots were aware the plane was in a stall, which occurs when a plane slows so much that the wings lose lift.
Ice was also identified as a probable factor in last July’s crash of an Air Algerie MD-83 in Mali, France’s BEA air crash investigator said in an interim report. It described the zone where the plane flew as “particularly active and highly dynamic, creating risks of severe icing and/or severe turbulence.” The cockpit-voice recorder from that plane was badly damaged, complicating the search for information.
Ice crystals in the fuel were blamed for having clogged the fuel-oil heat exchanger of each engine of British Airways Flight 38 on Jan. 17, 2008. The plane crash-landed just short of the runway at London’s Heathrow Airport, with 47 injuries and no fatalities.
Hans Weber, president of San Diego-based Tecop International, said investigators will need to ask about the quality of weather information available to pilots on the AirAsia flight.
“There are known deficiencies in air traffic control’s using modern technologies for providing up-to-date, real-time weather information, which is very important to maintain safety,” he said.